AMEREN ENERGY GENERATING COMPANY $250,000,000 6.30%SENIOR NOTES, SERIES I, DUE 2020 Underwriting Agreement

circumstances then prevailing, not misleading, the Company will give prompt notice thereof to the Representatives and, if requested by the Representatives, will prepare and furnish without charge to each Underwriter an Issuer Free Writing Prospectus or other document which will correct such conflict, statement or omission; provided, however, that this representation and warranty shall not apply to any statements or omissions in an Issuer Free Writing Prospectus made in reliance upon and in conformity with information furnished in writing to the Company by an Underwriter through the Representatives expressly for use therein.

7.             Whether or not any sale of the Securities is consummated, the Company covenants and agrees with the several Underwriters that the Company will pay or cause to be paid the following: (i) the fees, disbursements and expenses of any counsel for the Company and the Accountants in connection with the registration of the Securities under the 1933 Act and all other expenses in connection with the preparation, printing, reproduction and filing of the Registration Statement, any Preliminary Prospectus, any Issuer Free Writing Prospectus, the Pricing Disclosure Package and the Prospectus and amendments and supplements thereto and the mailing and delivering of copies thereof to the Underwriters and any dealers; (ii) the applicable SEC filing fees relating to the Securities within the time required by Rule 456(b)(1) under the 1933 Act without regard to the proviso thereof; (iii) the cost of printing or producing any agreement among Underwriters, this Agreement, the Indenture, any blue sky surveys, closing documents (including any compilations thereof) and any other documents in connection with the offering, purchase, sale and delivery of the Securities; (iv) all expenses (not to exceed $5,000) in connection with the qualification of the Securities for offering and sale under state securities laws as provided in Section 5(c) hereof, including the fees and disbursements of Underwriters’ Counsel in connection with such qualification and in connection with any such blue sky surveys; (v) any fees charged by securities rating services for rating the Securities; (vi) any filing fees incident to, and the fees and disbursements of Underwriters’ Counsel in connection with, any required review by the Financial Industry Regulatory Authority of the terms of the sale of the Securities; (vii) the cost of preparing certificates for the Securities; (viii) the fees and expenses of the Trustee and any agent of the Trustee and the fees and disbursements of counsel for the Trustee in connection with the Indenture and the Securities; and (ix) all other costs and expenses incurred by the Company incident to the performance of the Company’s obligations hereunder that are not otherwise specifically provided for in this Section 7.  It is understood, however, that, except as provided in this Section 7 and Sections 9 and 13 hereof, the Underwriters will pay all of their own costs and expenses, including the fees of Underwriters’ Counsel and any advertising expenses in connection with any offers the Underwriters may make.

8.             The obligations of the several Underwriters hereunder shall be subject, in the discretion of the Underwriters, to the condition that all representations and warranties and other statements of the Company contained herein are, at and as of the Applicable Time and the Time of Delivery, true and correct, the condition that the Company shall have performed all of its obligations hereunder theretofore to be performed, and the following additional conditions:

(a)           The Prospectus shall have been filed with the SEC pursuant to Rule 424(b) and Rule 430A, Rule 430B or Rule 430C under the 1933 Act within the applicable time period prescribed for such filing by the rules and regulations under the 1933 Act and in accordance with Section 5(a) hereof; the final term sheet contemplated by Section 5(a) hereof, and any other material required to be filed by the Company pursuant to Rule 433(d) under the 1933 Act, shall have been filed with the SEC within the applicable time period prescribed for such filings by Rule 433; no stop order suspending the effectiveness of the Registration Statement or any part thereof shall have been issued and no proceeding for that purpose or

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pursuant to Section 8A of the 1933 Act against the Company or related to the offering of the Securities shall have been initiated or threatened by the SEC and no notice of objection of the SEC to the use of the Registration Statement or any post-effective amendment thereto pursuant to Rule 401(g)(2) under the 1933 Act shall have been received; no stop order suspending or preventing the use of the Prospectus or any Issuer Free Writing Prospectus shall have been initiated or threatened by the SEC; and all requests for additional information on the part of the SEC shall have been complied with to the reasonable satisfaction of the Representatives.

(b)           At the Time of Delivery, Underwriters’ Counsel shall have furnished to the Representatives an opinion, dated the Time of Delivery, with respect to such matters as the Representatives may reasonably request, and Underwriters’ Counsel shall have received such documents and information as it may reasonably request to enable it to pass upon such matters.  In rendering such opinion, Underwriters’ Counsel may (i) state that such opinion is limited to matters covered by the federal laws of the United States of America and the laws of the States of Illinois and New York and (ii) rely (A) as to matters involving the application of the laws of the State of Illinois, upon the opinion of Craig W. Stensland, Associate General Counsel of Ameren Services Company, an affiliate of the Company, rendered pursuant to Section 8(c)(1) hereof and (B) as to matters of fact, to the extent deemed proper, on certificates of responsible officers of the Company and public officials.

(c)           (1)           At the Time of Delivery, Craig W. Stensland, Associate General Counsel of Ameren Services Company, an affiliate of the Company, shall have furnished to the Representatives an opinion, dated the Time of Delivery, in form and substance satisfactory to the Representatives, substantially to the effect that:

(i)            the Company has been duly incorporated and is validly existing as a corporation in good standing under the laws of the State of Illinois, with corporate power and authority to own its properties and conduct its business as described in the Pricing Disclosure Package and the Prospectus and to enter into and perform its obligations under, or as contemplated by, this Agreement;

(ii)           the Company is duly qualified to do business as a foreign corporation in good standing in all other jurisdictions in which its ownership or lease of property or the conduct of its business requires such qualification, except to the extent that the failure to be so qualified or to be in good standing would not reasonably be expected to have a Material Adverse Effect;

(iii)          this Agreement has been duly authorized, executed and delivered by the Company;;

(iv)          the Securities have been duly authorized by the Company and, when executed and authenticated in accordance with the provisions of the Indenture and issued and delivered by the Company pursuant to this Agreement against payment of the consideration set forth herein, will constitute valid and binding obligations of the Company, enforceable against the Company in accordance with their terms and the terms of the Indenture, subject to the Exceptions;

(v)           the Indenture has been duly authorized, executed and delivered by the Company and constitutes a valid and binding agreement of the Company, enforceable against the Company in accordance with its terms, subject to the Exceptions;

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(vi)          the issue and sale of the Securities by the Company, and the compliance by the Company with all of the provisions of the Securities, the Indenture and this Agreement, and the consummation of the transactions herein and therein contemplated, will not conflict with or result in a breach or violation of any of the terms or provisions of, or (with the giving of notice or lapse of time or both) constitute a default under, any indenture, mortgage, deed of trust, loan agreement or other agreement or instrument to which the Company is a party or by which the Company is bound or to which any of the property or assets of the Company is subject, which would reasonably be expected to have a Material Adverse Effect, nor will such action result in any violation of the provisions of the articles of incorporation, by-laws or similar organizational documents of the Company or any statute or any judgment, order, decree, rule or regulation of any court or governmental or regulatory agency or body having jurisdiction over the Company or any of its properties; and the execution, delivery and performance of the Securities, the Indenture and this Agreement and the consummation of the transactions herein and therein contemplated will not require the approval or consent of any holder or trustee of any debt or other obligations or securities of the Company which will not have been obtained; and

(vii)         no consent, approval, authorization, order, registration, filing or qualification of or with any court or government agency or body of the State of Illinois is legally required to be obtained for the issuance and sale of the Securities by the Company, or the consummation by the Company of the transactions contemplated by this Agreement or the Indenture, except such consents, approvals, authorizations, orders, registrations, filings or qualifications as may be required under state securities or blue sky laws of any jurisdiction in connection with the purchase and distribution of the Securities by the Underwriters, as to which counsel need not express an opinion.

In rendering such opinion, such counsel may (i) state that such opinion is limited to matters covered by the laws of the States of Illinois and New York and (ii) rely (A) as to matters involving the application of the laws of the State of New York, on the opinion of Morgan, Lewis & Bockius LLP, special counsel to the Company, rendered pursuant to Section 8(d) hereof and (B) as to matters of fact, to the extent deemed proper, on certificates of responsible officers of the Company and public officials.  Such counsel’s opinion may further state that it is addressed to the Representatives and is rendered solely for their benefit and the benefit of the other Underwriters and may not be relied upon in any manner by any other person (other than Morgan, Lewis & Bockius LLP and Underwriters’ Counsel as to certain matters involving the application of the laws of the State of Illinois in their respective opinions to the Representatives on the date of such opinion) without such counsel’s prior written consent.

(2)           At the Time of Delivery, Steven R. Sullivan, Senior Vice President, General Counsel and Secretary of the Company, shall have furnished to the Representatives an opinion, dated the Time of Delivery, in form and substance satisfactory to the Representatives, substantially to the effect that:

(i)            other than as set forth in the Pricing Disclosure Package and the Prospectus, there are no legal or governmental proceedings pending to which the Company is a party or of which any property of the Company is the subject that, if determined adversely to the Company, would individually or in the aggregate reasonably be expected to have a Material Adverse Effect, and, to such counsel’s knowledge, no such proceedings are threatened by governmental authorities or others; and the statements included or incorporated by reference in the Pricing Disclosure Package and

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the Prospectus describing any legal proceedings or material contracts or agreements relating to the Company fairly summarize such matters;

(ii)           the Company is not, and, after giving effect to the offering and sale of the Securities and the application of the net proceeds thereof, will not be, an “investment company,” or an entity “controlled” by an investment company, as such terms are defined in the Investment Company Act of 1940, as amended;

(iii)          the Indenture has been duly qualified under the 1939 Act;

(iv)          to the best of my knowledge, each contract or document material to the Company described in the Pricing Prospectus and the Prospectus is in full force and effect in accordance with its terms, except where a failure to be in full force and effect would not cause a Material Adverse Effect;

(v)           the statements set forth in the Prospectus under the captions “Description of Senior Notes” and “Description of the Senior Debt Securities and the Indenture,” insofar as they purport to constitute a summary of the terms of the Securities and the Indenture, and under the captions “Plan of Distribution” and “Underwriting” (except with respect to the ninth, tenth, eleventh and twelfth complete paragraphs under the caption “Underwriting,” upon which such counsel need not pass), insofar as such statements summarize legal matters, agreements, documents or proceedings discussed therein, are accurate and fair summaries of such legal matters, agreements, documents or proceedings in all material respects;

(vi)          the documents incorporated by reference in the Pricing Disclosure Package and the Prospectus (other than the financial statements and related schedules and other financial and statistical data included or incorporated by reference therein, as to which such counsel need express no opinion), when they were filed with the SEC complied as to form in all material respects with the requirements of the 1933 Act and the 1934 Act, as applicable, and the rules and regulations of the SEC thereunder;

(vii)         the Registration Statement, as of the date of filing of the Company’s latest Annual Report on Form 10-K, and the Pricing Prospectus and the Prospectus as amended or supplemented, as of the date each was filed with the SEC pursuant to Rule 424(b) under the 1933 Act (in each case, other than the financial statements and related schedules and other financial and statistical data included or incorporated by reference therein, as to which such counsel need express no opinion or belief), complied as to form in all material respects with the requirements of the 1933 Act and the 1939 Act and the rules and regulations thereunder; although such counsel does not assume any responsibility for the accuracy, completeness or fairness of the statements contained in the Registration Statement, the Pricing Disclosure Package or the Prospectus, except for those referred to in the opinion in subsection (v) of this Section 8(c)(2) and those that relate to such counsel, such counsel has no reason to believe that (1) the Registration Statement (other than the financial statements and related schedules and other financial and statistical data included or incorporated by reference therein, as to which such counsel need express no opinion or belief), as of the latest date as of which any part of the Registration Statement is deemed to have become effective under the 1933 Act in accordance with Section 11(d) of the 1933 Act and Rule 430B under the 1933 Act, contained an untrue statement of a material fact or omitted to state a material fact required to be stated therein or necessary to make the statements therein not

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misleading, (2) the Pricing Disclosure Package (other than the financial statements and related schedules and other financial and statistical data included or incorporated by reference therein, as to which such counsel need express no opinion or belief), at the Applicable Time, contained any untrue statement of a material fact or omitted to state a material fact necessary in order to make the statements therein, in the light of the circumstances under which they were made, not misleading or (3) the Prospectus (other than the financial statements and related schedules and other financial and statistical data included or incorporated by reference therein, as to which such counsel need express no opinion or belief), as of its date or on the date of such opinion, contained or contains an untrue statement of a material fact or omitted or omits to state a material fact necessary in order to make the statements therein, in the light of the circumstances under which they were made, not misleading; the Registration Statement has become, and as of the date of such opinion is, effective under the 1933 Act; any required filing of each Preliminary Prospectus and the Prospectus as amended or supplemented, pursuant to Rule 424(b) under the 1933 Act has been made in the manner and within the time period required by the applicable paragraph of such Rule 424(b); any required filing of the Issuer Free Writing Prospectus, pursuant to Rule 433 under the 1933 Act, has been made in the manner and within the time period required by such Rule 433; and, to the best of such counsel’s knowledge, no stop order suspending the effectiveness of the Registration Statement has been issued, and no proceedings for that purpose have been instituted or threatened under Section 8 or Section 8A of the 1933 Act; and

(viii)        the FERC Order is in full force and effect and is sufficient to authorize the transactions contemplated by the Agreement to the extent authorization is required; no other consent, approval, authorization, order, registration, filing or qualification of or with any court or governmental agency or body of the United States of America is legally required to be obtained for the issue and sale of the Securities by the Company, or the consummation by the Company of the transactions contemplated by this Agreement or the Indenture, except such as have been obtained under the 1933 Act and the 1939 Act and such consents, approvals, authorizations, orders, registrations, filings or qualifications as may be required under state securities or blue sky laws of any jurisdiction in connection with the purchase and distribution of the Securities by the Underwriters, as to which counsel need not express an opinion.

Such opinion shall also state that such counsel has no knowledge of any litigation, pending or threatened, that challenges the validity of the Securities, the Indenture or this Agreement, or that seeks to enjoin the performance of the Company’s obligations hereunder or thereunder or that might reasonably be expected to have a Material Adverse Effect except as described in the Pricing Disclosure Package and the Prospectus.

In rendering such opinion, such counsel may state that such opinion is limited to matters covered by the federal laws of the United States of America and the laws of the State of Missouri and rely as to matters of fact, to the extent deemed proper, on certificates of responsible officers of the Company and public officials.  Such counsel’s opinion may further state that it is addressed to the Representatives and is rendered solely for their benefit and the benefit of the other Underwriters and may not be relied upon in any manner by any other person without such counsel’s prior written consent.

(d)           At the Time of Delivery, Morgan, Lewis & Bockius LLP, special counsel to the Company, shall have furnished to the Representatives an opinion, dated the Time of Delivery, in form and substance satisfactory to the Representatives, with respect to the matters

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covered in paragraphs (iii), (iv), (v) and (vii) (with respect to the State of New York) of subsection (c)(1) above and paragraphs (ii), (iii), (v), (vi), (vii) and (viii) of subsection (c)(2) above, as well as such other related matters as the Representatives may reasonably request to enable them to pass upon such matters.  In addition, such counsel shall opine that the statements set forth in the Pricing Prospectus and the Prospectus under the caption “Material United States Federal Income Tax Consequences,” to the extent that they purport to constitute summaries of matters of law or regulation or legal conclusions, are accurate and fair in all material respects.  In rendering such opinion, such counsel may (i) state that such opinion is limited to matters covered by the federal laws of the United States of America and the laws of the States of Illinois and New York and (ii) rely (A) as to matters involving the application of the laws of the State of Illinois, upon the opinion of Craig W. Stensland, Associate General Counsel of Ameren Services Company, an affiliate of the Company, rendered pursuant to Section 8(c)(1) hereof and (B) as to matters of fact, to the extent deemed proper, on certificates of responsible officers of the Company and public officials.  Such opinion may contain a legend pursuant to Internal Revenue Service Circular 230.

(e)           On the date of this Agreement and at the Time of Delivery, the Accountants shall have furnished to the Representatives letters, dated the date of this Agreement and the Time of Delivery, respectively, in form and substance satisfactory to the Representatives, to the effect set forth in Annex I hereto.

(f)            (i) The Company shall not have sustained, since the date of the most recent audited consolidated financial statements included or incorporated by reference in the Pricing Prospectus, any loss or interference with their business from fire, explosion, flood or other calamity, whether or not covered by insurance, or from any labor dispute or court or governmental action, order or decree, otherwise than as set forth in the Pricing Prospectus, and (ii) since the respective dates as of which information is given in the Pricing Prospectus, there shall not have been any change, or any development involving a prospective change, in or affecting the general affairs, management, financial position, stockholders’ equity or consolidated results of operations of the Company or any Ameren Entity (to the extent such change or development affects the ability of such Ameren Entity to perform its obligations under the Transaction Documents to which it is a party), otherwise than as set forth or contemplated in the Pricing Prospectus, the effect of which, in any such case referred to in clause (i) or (ii) above, is, in the judgment of the Representatives, so material and adverse as to make it impracticable or inadvisable to proceed with the public offering or the delivery of the Securities on the terms and in the manner contemplated in the Pricing Disclosure Package and the Prospectus.

(g)           On or after the Applicable Time, (i) no downgrading shall have occurred in the rating accorded the Company’s debt securities by any Rating Agency, and (ii) no such Rating Agency shall have publicly announced that it has under surveillance or review, with possible negative implications, its rating of any of the Company’s debt securities, unless such surveillance or review has been publicly announced prior to the Applicable Time.

(h)           On or after the Applicable Time, there shall not have occurred any of the following: (i) a suspension or material limitation in trading in securities generally by the SEC, the New York Stock Exchange or the Nasdaq Stock Market or any setting of minimum or maximum prices for trading thereon; (ii) a suspension or material limitation in trading in the Company’s securities by the SEC, the New York Stock Exchange, the American Stock Exchange or the Nasdaq Stock Market; (iii) a general moratorium on commercial banking activities declared by Federal, New York state or Illinois state authorities or a material disruption has occurred in

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commercial banking or securities settlement or clearance services in the United States; (iv) any outbreak or escalation of hostilities involving the United States or the declaration by the United States of a national emergency or war; or (v) the occurrence of any other calamity or crisis or any change in financial, political or economic conditions in the United States or elsewhere, if the effect of any event specified in clause (iv) or (v), in the judgment of the Representatives, makes it impracticable or inadvisable to proceed with the public offering or the delivery of the Securities on the terms and in the manner contemplated in the Pricing Disclosure Package and the Prospectus.

(i)            On or prior to the Time of Delivery, the Representatives shall have received satisfactory evidence that the Securities have received ratings of BBB- or higher by Standard & Poor’s Ratings Services, Baa3 or higher by Moody’s Investors Service, Inc., and BBB+ or higher by Fitch, Inc., and that such ratings are in effect at the Time of Delivery.

(j)            The Company shall have complied with the provisions of Section 5(f) hereof with respect to the furnishing of the Prospectus and each Issuer Free Writing Prospectus on the New York Business Day next succeeding the date of this Agreement.

(k)           At the Time of Delivery, the Company shall have furnished or caused to be furnished to the Representatives a certificate or certificates, dated the Time of Delivery, of (i) the Chief Executive Officer and President, any Senior Vice President or any Vice President of the Company and (ii) the Treasurer of the Company in which such officers shall state that: the representations and warranties of the Company in this Agreement are true and correct in all material respects (except that any such representations and warranties that are qualified in respect of materiality or Material Adverse Effect shall be true and correct in all respects) at and as of the Time of Delivery, that the Company has complied with all agreements and has satisfied all conditions on its part to be performed or satisfied hereunder at or prior to the Time of Delivery and that, subsequent to the respective dates as of which information is given in the Pricing Prospectus, there has been no material adverse change, or any development involving a prospective material adverse change, in or affecting the general affairs, management, financial position, stockholders’ equity or consolidated results of operations of the Company or any Ameren Entity (to the extent such change or development affects the ability of such Ameren Entity to perform its obligations under the Transaction Documents to which it is a party) otherwise than as described in the Pricing Prospectus.

(l)            The FERC Order shall be in full force and effect at the Time of Delivery.

(m)          At the Time of Delivery, Underwriters’ Counsel shall have been furnished with all such documents, certificates and opinions as Underwriters’ Counsel may reasonably request and that are customary for transactions of a similar nature, in order to evidence the accuracy and completeness of any of the representations, warranties, certificates or other written statements of the Company provided to the Representatives pursuant to this Agreement, the performance of any of the covenants of the Company, or the fulfillment of any of the conditions herein contained.  All proceedings taken by the Company at or prior to the Time of Delivery in connection with the authorization, issuance and sale of the Securities as contemplated by this Agreement, including, without limitation, the execution of this Agreement, shall be reasonably satisfactory in form and substance to the Representatives and Underwriters’ Counsel.

In case any of the conditions specified above in this Section 8 shall not have been fulfilled, this Agreement may be terminated by the Representatives upon mailing or

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otherwise delivering written notice thereof to the Company.  Any such termination shall be without liability of either party to the other party except as otherwise provided in Section 7 hereof and except for any liability under Section 9 hereof.

9.             (a)           The Company will indemnify and hold harmless each Underwriter against any losses, claims, damages, liabilities or expenses, as and when incurred, to which such Underwriter may become subject, joint or several, under the 1933 Act or otherwise, insofar as such losses, claims, damages, liabilities or expenses (or actions or claims in respect thereof), arise out of or are based upon an untrue statement or alleged untrue statement of a material fact contained in the Registration Statement, any Preliminary Prospectus, the Pricing Prospectus or the Prospectus, or any amendment or supplement thereto, any Issuer Free Writing Prospectus or any “issuer information” filed or required to be filed pursuant to Rule 433(d) under the 1933 Act, or arise out of or are based upon the omission or alleged omission to state therein a material fact required to be stated therein or necessary to make the statements therein not misleading, and will promptly reimburse such Underwriter for any reasonable expenses (including reasonable fees and expenses for no more than one law firm for the Underwriters) when and as incurred by such Underwriter in connection with investigating or defending any such action or claim; provided, however, that the Company shall not be liable in any such case to an Underwriter to the extent that any such loss, claim, damage, liability or expense arises out of or is based upon an untrue statement or alleged untrue statement or omission or alleged omission made in the Registration Statement, any Preliminary Prospectus, the Pricing Prospectus or the Prospectus, or any amendment or supplement thereto, or any Issuer Free Writing Prospectus, in reliance upon and in conformity with written information furnished to the Company by an Underwriter through the Representatives expressly for use therein.

(b)           Each Underwriter, severally, will indemnify and hold harmless the Company against any losses, claims, damages, liabilities or expenses to which the Company may become subject, under the 1933 Act or otherwise, insofar as such losses, claims, damages, liabilities or expenses (or actions or claims in respect thereof) arise out of or are based upon an untrue statement or alleged untrue statement of a material fact contained in the Registration Statement, any Preliminary Prospectus, the Pricing Prospectus or the Prospectus, or any amendment or supplement thereto, or any Issuer Free Writing Prospectus, or arise out of or are based upon the omission or alleged omission to state therein a material fact required to be stated therein or necessary to make the statements therein not misleading, in each case to the extent, but only to the extent, that such untrue statement or alleged untrue statement or omission or alleged omission was made in the Registration Statement, any Preliminary Prospectus, the Pricing Prospectus or the Prospectus, or any amendment or supplement thereto, or any Issuer Free Writing Prospectus, in reliance upon and in conformity with written information furnished to the Company by any Underwriter through the Representatives expressly for use therein, and will reimburse the Company for any reasonable expenses (including reasonable fees and expenses for no more than one law firm for the Company) when and as incurred by the Company in connection with investigating or defending any such action or claim.

(c)           Promptly after receipt by an indemnified party under Section 9(a) or 9(b) hereof of notice of the commencement of any action, such indemnified party shall, if a claim in respect thereof is to be made against the indemnifying party under Section 9(a) or 9(b) hereof, notify such indemnifying party in writing of the commencement thereof, but the omission so to notify such indemnifying party shall not relieve such indemnifying party from any liability except to the extent that it has been prejudiced in any material respect by such failure or from any

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liability that it may have to any such indemnified party otherwise than under Section 9(a) or 9(b) hereof.  In case any such action shall be brought against any such indemnified party and it shall notify such indemnifying party of the commencement thereof, such indemnifying party shall be entitled to participate therein and, to the extent that it shall wish, jointly with any other indemnifying party under Section 9(a) or 9(b) hereof similarly notified, to assume the defense thereof, with counsel satisfactory to such indemnified party (who shall not, except with the consent of such indemnified party, be counsel to such indemnifying party), and, after notice from such indemnifying party to such indemnified party of its election so to assume the defense thereof, such indemnifying party shall not be liable to such indemnified party under Section 9(a) or 9(b) hereof for any legal expenses of other counsel or any other expenses, in each case subsequently incurred by such indemnified party, in connection with the defense thereof other than reasonable costs of investigation.  Notwithstanding the foregoing, the indemnified party shall have the right to employ separate counsel at the indemnifying party’s expense and to control its defense of such action if (i) the indemnifying party and the indemnified party agree to the retention of that counsel, (ii) the indemnifying party does not assume the defense of such action in a timely manner or (iii) the indemnified party reasonably objects to such assumption on the ground that there may be legal defenses available to it that are different from or in addition to those available to the indemnifying party or another indemnified party.  No indemnifying party shall, without the written consent of the indemnified party, effect the settlement or compromise of, or consent to the entry of any judgment with respect to, any pending or threatened action or claim in respect of which indemnification or contribution may be sought hereunder (whether or not the indemnified party is an actual or potential party to such action or claim) unless such settlement, compromise or judgment (x) includes an unconditional release of the indemnified party from all liability arising out of such action or claim and (y) does not include any statement as to, or an admission of, fault, culpability or a failure to act by or on behalf of any indemnified party.

(d)           If the indemnification provided for in this Section 9 is unavailable to or insufficient to hold harmless an indemnified party under Section 9(a) or 9(b) hereof in respect of any losses, claims, damages, liabilities or expenses (or actions or claims in respect thereof) referred to therein, then each indemnifying party under Section 9(a) or 9(b) hereof shall contribute to the amount paid or payable by such indemnified party as a result of such losses, claims, damages, liabilities or expenses (or actions or claims in respect thereof) in such proportion as is appropriate to reflect the relative benefits received by the Company on the one hand and the Underwriters on the other hand from the offering of the Securities.  If, however, the allocation provided by the immediately preceding sentence is not permitted by applicable law or if the indemnified party failed to give the notice required under Section 9(c) hereof, then each such indemnifying party shall contribute to such amount paid or payable by such indemnified party in such proportion as is appropriate to reflect not only such relative benefits but also the relative fault of the Company on the one hand and the Underwriters on the other hand in connection with the statements or omissions that resulted in such losses, claims, damages, liabilities or expenses (or actions or claims in respect thereof), as well as any other relevant equitable considerations.  The relative benefits received by the Company on the one hand and the Underwriters on the other hand shall be deemed to be in the same proportion as the total net proceeds from such offering (before deducting expenses) received by the Company bear to the total underwriting discounts and commissions received by the Underwriters, in each case as set forth in the table on the cover page of the Prospectus.  The relative fault of the Company on the one hand and the Underwriters on the other hand shall be determined by reference to, among other things, whether the untrue or alleged untrue statement of a material fact or the omission or alleged omission to state a material fact relates to information supplied by the Company or the Underwriters and the parties’ relative intent, knowledge, access to

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information and opportunity to correct or prevent such statement or omission.  The Company and the Underwriters agree that it would not be just and equitable if contribution pursuant to this Section 9(d) were determined by pro rata allocation (even if the Underwriters were treated as one entity for such purpose) or by any other method of allocation that does not take account of the equitable considerations referred to above in this Section 9(d).  The amount paid or payable by such an indemnified party as a result of the losses, claims, damages, liabilities or expenses (or actions or claims in respect thereof) referred to above in this Section 9(d) shall be deemed to include any legal or other expenses incurred by such indemnified party in connection with investigating or defending any such action or claim.  Notwithstanding the provisions of this Section 9(d), no Underwriter shall be required to contribute any amount in excess of the amount by which the total price at which the Securities underwritten by such Underwriter and distributed to the public were offered to the public exceeds the amount of any damages that such Underwriter has otherwise been required to pay by reason of such untrue or alleged untrue statement or omission or alleged omission.  No person guilty of fraudulent misrepresentation (within the meaning of Section 11(f) of the 1933 Act) shall be entitled to contribution from any person who was not guilty of such fraudulent misrepresentation.  The Underwriters’ obligations in this Section 9(d) to contribute are several in proportion to their respective underwriting obligations and not joint.

(e)           The obligations of the Company under this Section 9 shall be in addition to any liability that the Company may otherwise have and shall extend, upon the same terms and conditions, to each officer, director, employee, agent or other representative and to each person, if any, who controls each Underwriter within the meaning of the 1933 Act or the 1934 Act and each broker-dealer affiliate of any Underwriter; and the obligations of the Underwriters under this Section 9 shall be in addition to any liability that the respective Underwriters may otherwise have and shall extend, upon the same terms and conditions, to each officer, director, employee, agent or other representative and to each person, if any, who controls the Company within the meaning of the 1933 Act or the 1934 Act.

10.           The respective indemnities, agreements, representations, warranties and other statements of the Company and the several Underwriters, as set forth in this Agreement or made by or on behalf of the Company or the Underwriters, respectively, pursuant to this Agreement, shall remain in full force and effect, regardless of any investigation (or any statement as to the results thereof) made by or on behalf of any Underwriter, any of its officers, directors, employees, agents or other representatives or controlling persons, or the Company, any officer or director of the Company who signed the Registration Statement or any controlling person of the Company, and shall survive delivery of and payment for the Securities.

11.           All notices and other communications hereunder shall be in writing and shall be deemed to have been duly given if mailed or transmitted by any standard form of telecommunication.  Notices to the Underwriters shall be directed to Barclays Capital Inc., 745 Seventh Avenue, New York, New York 10019, Attention: Syndicate Registration, facsimile: (646) 834-8133, Morgan Stanley & Co. Incorporated, 1585 Broadway, New York, New York 10036, Attention: Syndicate Desk, facsimile: (212) 507-5089, RBS Securities Inc., 600 Washington Boulevard, Stamford, Connecticut 06901, Attention: Debt Capital Markets Syndicate, facsimile: (203) 873-4534 and Scotia Capital (USA) Inc., 165 Broadway — 25th Floor, New York, New York 10006, Attention: Debt Capital Markets, facsimile: (212) 225-6550; and notices to the Company shall be directed to Ameren Energy Generating Company, 1901 Chouteau Avenue, St. Louis, Missouri 63103, facsimile: (314) 554-3066, Attention: Treasurer, with a copy to the office of General Counsel, facsimile: (314) 554-4014.

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12.           (a)           If any Underwriter shall default in its obligation to purchase the Securities which it has agreed to purchase hereunder, the Representatives may in their discretion arrange for themselves or another party or other parties to purchase such Securities on the terms contained herein.  If within thirty-six hours after such default by any Underwriter the Representatives do not arrange for the purchase of such Securities, then the Company shall be entitled to a further period of thirty-six hours within which to procure another party or other parties satisfactory to the Representatives to purchase such Securities on such terms.  In the event that, within the respective prescribed periods, the Representatives notify the Company that they have so arranged for the purchase of such Securities, or the Company notifies the Representatives that it has so arranged for the purchase of such Securities, the Representatives or the Company shall have the right to postpone the Time of Delivery for a period of not more than seven days, in order to effect whatever changes may thereby be made necessary in the Registration Statement or the Prospectus, or in any other documents or arrangements, and the Company agrees to file promptly any amendments or supplements to the Registration Statement or the Prospectus which in the opinion of the Representatives may thereby be made necessary.  The term “Underwriter” as used in this Agreement shall include any person substituted under this Section 12 with like effect as if such person had originally been a party to this Agreement with respect to such Securities.

(b)           If, after giving effect to any arrangements for the purchase of the Securities of a defaulting Underwriter or Underwriters by the Representatives and the Company as provided in Section 12(a) hereof, the aggregate principal amount of such Securities which remains unpurchased does not exceed one-eleventh of the aggregate principal amount of all the Securities, then the Company shall have the right to require each non-defaulting Underwriter to purchase the principal amount of Securities which such Underwriter agreed to purchase hereunder and, in addition, to require each non-defaulting Underwriter to purchase its pro rata share (based on the principal amount of Securities which such Underwriter agreed to purchase hereunder) of the Securities of such defaulting Underwriter or Underwriters for which such arrangements have not been made; but nothing herein shall relieve a defaulting Underwriter from liability for its default.

(c)           If, after giving effect to any arrangements for the purchase of the Securities of a defaulting Underwriter or Underwriters by the Representatives and the Company as provided in Section 12(a) hereof, the aggregate principal amount of such Securities which remains unpurchased exceeds one-eleventh of the aggregate principal amount of all the Securities, or if the Company shall not exercise the right described in Section 12(b) hereof to require non-defaulting Underwriters to purchase Securities of a defaulting Underwriter or Underwriters, then this Agreement shall thereupon terminate, without liability on the part of any non-defaulting Underwriter or the Company, except for the expenses to be borne by the Company and the Underwriters as provided in Section 7 hereof and the indemnity and contribution agreements in Section 9 hereof; but nothing herein shall relieve a defaulting Underwriter from liability for its default.

13.           If this Agreement shall be terminated pursuant to Section 12 hereof, the Company shall not then be under any liability to any Underwriter except as provided in Sections 7 and 9 hereof; but, if for any other reason, including if any of the conditions in Section 8 hereof have not been fulfilled, the Securities are not delivered by or on behalf of the Company as provided herein or the Company does not comply with its other obligations as provided herein, the Company will reimburse the Underwriters through the Representatives for all out-of-pocket expenses approved in writing by the Representatives, including fees and disbursements of Underwriters’ Counsel, reasonably incurred by the Underwriters in making preparations for

24

the purchase, sale and delivery of the Securities, but the Company shall then be under no further liability to any Underwriter except as provided in Sections 7 and 9 hereof.

14.           The Company hereby acknowledges that the Underwriters are acting solely in the capacity of an arm’s length contractual counterparty to the Company with respect to the offering of Securities contemplated hereby (including in connection with determining the terms of the offering) and not as a financial advisor or a fiduciary to, or an agent of, the Company or any other person.  Additionally, neither the Representatives nor any other Underwriters are advising the Company or any other person as to any legal, tax, investment, accounting or regulatory matters in any jurisdiction with respect to the offering of Securities contemplated hereby.  The Company shall consult with its own advisors concerning such matters and shall be responsible for making its own independent investigation and appraisal of the transactions contemplated hereby, and the Underwriters shall have no responsibility or liability to the Company with respect thereto.  Any review by the Underwriters of the Company, the transactions contemplated hereby or other matters relating to such transactions will be performed solely for the benefit of the Underwriters and shall not be on behalf of the Company.

15.           The rights and duties of the parties to this Agreement shall, pursuant to New York General Obligations Law Section 5-1401, be governed by the law of the State of New York.  This Agreement shall be binding upon, and inure solely to the benefit of, the Company and the Underwriters except to the extent provided in Section 9(e) hereof, and their respective heirs, executors, administrators, successors and assigns, and no other person shall acquire or have any right under or by virtue of this Agreement.  No person who purchases any of the Securities from the Underwriters shall be deemed a successor or assign by reason merely of such purchase.  This Agreement may be executed by any one or more of the parties hereto in any number of counterparts, each of which shall be deemed to be an original, but all such respective counterparts shall together constitute one and the same instrument.  Time shall be of the essence of this Agreement.  As used herein, the term “business day” shall mean any day when the SEC’s office in Washington, D.C. is open for business.  The word “or” shall not be exclusive, and all references in this Agreement to the words “herein,” “hereof,” “hereunder” and other words of similar import refer to this Agreement as a whole and not to any particular Section or subdivision hereof, and the captions to such Sections and subdivisions are for convenience only and shall not affect the construction hereof.  The Company is authorized, subject to applicable law, to disclose any and all aspects of this potential transaction that are necessary to support any U.S. federal or state income tax benefits expected to be claimed with respect to such transaction, without the Underwriters imposing any limitation of any kind.

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If the foregoing is in accordance with your understanding, please sign and return to the Company the enclosed duplicate hereof, whereupon this Agreement will become a binding agreement between the Company and the Underwriters in accordance with its terms.

For themselves and as Representatives of the

other Underwriters named in Schedule I hereto

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SCHEDULE I

I-1

SCHEDULE II

(a)           Issuer Free Writing Prospectuses to be included in the Pricing Disclosure Package:  Pricing Term Sheet dated November 12, 2009 (attached hereto as Exhibit A).

(b)           Issuer Free Writing Prospectuses not included in the Pricing Disclosure Package: None.

(c)           Additional Documents Incorporated by Reference: None.

II-1

Exhibit A

Filed Pursuant to Rule 433

Registration No. 333-155416-02

November 12, 2009

Pricing Term Sheet

The issuer has filed a registration statement (including a prospectus) with the SEC for the offering to which this communication relates.  Before you invest, you should read the prospectus in that registration statement and other documents the issuer has filed with the SEC for more complete information about the issuer and this offering.  You may get these documents for free by visiting EDGAR on the SEC Web site at www.sec.gov.  Alternatively, the issuer, any underwriter or any dealer participating in the offering will arrange to send you the prospectus if you request it by calling Barclays Capital Inc. toll-free at ###-###-####, Morgan Stanley & Co. Incorporated toll-free at ###-###-####, RBS Securities Inc. toll-free at 1 ###-###-#### or Scotia Capital (USA) Inc. toll-free at ###-###-####.

II-2

*  A securities rating is not a recommendation to buy, sell or hold securities and should be evaluated independently of any other rating.  The rating is subject to revision or withdrawal at any time by the assigning rating organization.

II-3

Annex I

Pursuant to Section 8(d) of the Underwriting Agreement, the Accountants shall furnish letters to the Underwriters to the effect that:

(i)            they are an independent registered public accounting firm with respect to the Company and its subsidiary within the meaning of the 1933 Act and the applicable rules and regulations thereunder adopted by the SEC and the Public Company Accounting Oversight Board (United States) (PCAOB);