Supplement to Note Purchase Agreement (this Supplement) AEP Transmission Company, LLC 1 Riverside Plaza Columbus, Ohio 43215

Reference is made to that certain Note Purchase Agreement, dated as of October 18, 2012 between AEP Transmission Company, LLC, a Delaware limited liability company, and each of the Initial Purchasers named in the Initial Purchaser Schedule attached thereto (the “Agreement”). Terms used but not defined herein shall have the respective meanings set forth in the Agreement.

As contemplated in Section 2.2 of the Agreement, the Company agrees with you as follows:

A.    Subsequent Series of Notes. The Company has authorized and will create a Subsequent Series of Notes to be called the “Series B Notes.” Said Series B Notes will consist of (a) U.S. $50,000,000 aggregate principal amount of 2.73% Senior Notes, Series B, Tranche A, due November 7, 2018 (the “Series B Tranche A Notes”), (b) U.S. $60,000,000 aggregate principal amount of 4.05% Senior Notes, Series B, Tranche B, due November 7, 2023 (the “Series B Tranche B Notes”), (c) U.S. $60,000,000 aggregate principal amount of 4.38% Senior Notes, Series B, Tranche C, due November 7, 2028 (the “Series B Tranche C Notes”), (d) U.S. $100,000,000 aggregate principal amount of 5.32% Senior Notes, Series B, Tranche D, due November 7, 2043 (the “Series B Tranche D Notes”); (e) U.S. $30,000,000 aggregate principal amount of 5.42% Senior Notes, Series B, Tranche E, due April 30, 2044 (the “Series B Tranche E Notes”), and (f) U.S. $100,000,000 aggregate principal amount of 5.52% Senior Notes, Series B, Tranche F, due October 30, 2044 (the “Series B Tranche F Notes”; the Series B Tranche A Notes, the Series B Tranche B Notes, the Series B Tranche C Notes, the Series B Tranche D Notes, the Series B Tranche E Notes and the Series B Tranche F Notes are hereinafter collectively referred to as the “Series B Notes”, such term to include any such notes issued in substitution therefor pursuant to Section 13 of the Agreement). The Series B Tranche A Notes, the Series B Tranche B Notes, the Series B Tranche C Notes, the Series B Tranche D Notes, the Series B Tranche E Notes and the Series B Tranche F Notes shall be substantially in the form set out in Exhibit 1-A, 1-B, 1-C, 1-D, 1-E and 1-F to this Supplement, respectively, with such changes therefrom, if any, as may be approved by you and the Company.

B.    Purchase and Sale of Series B Notes. The Company hereby agrees to sell to each Supplemental Purchaser set forth on the Supplemental Purchaser Schedule attached hereto (collectively, the “Series B Purchasers”) and, subject to the terms and conditions in the Agreement and herein set forth, each Series B Purchaser agrees to purchase from the Company, at a Series B Closing provided for in Section C to this Supplement, Series B Notes in the principal amount and in the tranche set opposite each Series B Purchaser’s name in the Supplemental Purchaser Schedule at the purchase price of 100% of the principal amount thereof. The obligations of the Series B Purchasers hereunder are several and not joint obligations, and no Series B Purchaser shall have any liability to any Person for the performance or non-performance of any obligation by any other Series B Purchaser hereunder.

C.    Execution Date; Series B Closings. The execution and delivery of this Supplement will be made at the offices of Winston & Strawn LLP, 200 Park Avenue, New York, New York 10166 on November 7, 2013 (the “Series B Execution Date”).

The sale and purchase of the Series B Notes to be purchased by each Series B Purchaser shall occur at the offices of Winston & Strawn LLP, 200 Park Avenue, New York, New York 10166 at 10:00 a.m. Eastern Standard Time, at no more than three closings (individually, a “Series B Closing” and, collectively, the “Series B Closings”). The first Series B Closing, at which Series B Closing the Series B Tranche A Notes, the Series B Tranche B Notes the Series B Tranche C Notes and the Series B Tranche D Notes are, subject to this Section C and Section D to this Supplement, to be purchased, shall be held on November 7, 2013 (the “First Series B Closing”); the second Series B Closing, at which Series B Closing the Series B Tranche E Notes are, subject to this Section C and Section D to this Supplement, to be purchased, shall be held on April 30, 2014 (the “Second Series B Closing”), and the third Series B Closing, at which Series B Closing the Series B Tranche F Notes are, subject to this Section C and Section D, to be purchased, shall be held on October 30, 2014 (the “Third Series B Closing”). At each Series B Closing, the Company will deliver to each Series B Purchaser the Series B Notes of the tranche to be purchased by such Series B Purchaser at such Series B Closing in the form of a single Series B Note of such tranche (or such greater number of Series B Notes in denominations of at least $100,000 as such Series B Purchaser may request) dated the date of such Series B Closing and registered in such Series B Purchaser’s name (or in the name of its nominee), against payment by such Series B Purchaser of the purchase price thereof by transfer of immediately available funds for credit to the Company’s account on the date of such Series B Closing (which account shall be specified in a notice to each such Series B Purchaser at least three Business Days prior to each Series B Closing). If at such Series B Closings the Company shall fail to tender such Series B Notes to any Series B Purchaser as provided above in this Section C, or any of the conditions specified in Section D to this Supplement shall not have been fulfilled to such Series B Purchaser’s satisfaction, such Series B Purchaser shall, at its election, be relieved of all further obligations under this Supplement and the Agreement, without thereby waiving any rights such Series B Purchaser may have by reason of such failure or such nonfulfillment.

D.    Conditions to Series B Closings. The obligation of each Series B Purchaser to execute and deliver this Supplement on the Series B Execution Date is subject to the representations and warranties of the Company in Section 5 of the Agreement, as supplemented,

amended or superseded by the representations and warranties set forth in Exhibit A hereto, being correct when made on the Series B Execution Date. The obligations of each Series B Purchaser to purchase and pay for the Series B Notes to be purchased by such Series B Purchaser hereunder at a Series B Closing is subject to the satisfaction, on or before the date of such Series B Closing, of the conditions set forth in Section 4 of the Agreement, provided that the reference to Chapman and Cutler LLP in Section 4.4(c) of the Agreement shall be deemed to be a reference to Winston & Strawn LLP, and to the following additional conditions:

(a)    Except as supplemented, amended or superseded by the representations and warranties set forth in Exhibit A hereto, each of the representations and warranties of the Company set forth in Section 5 of the Agreement shall be correct as of the date of each Series B Closing and the Company shall have delivered to such Series B Purchaser an Officer’s Certificate, dated the date of such Series B Closing, certifying that such condition has been fulfilled.

(b)    Contemporaneously with each Series B Closing, the Company shall sell to each Series B Purchaser, and each Series B Purchaser shall purchase, the Series B Notes to be purchased by such Series B Purchaser on the date of such Series B Closing as specified in the Supplemental Purchaser Schedule.

E.    Prepayments. The Series B Notes shall be subject to prepayment only (a) pursuant to the required prepayments, if any, specified in clause (x) below; and (b) pursuant to the optional prepayments specified in clause (y) below.

(x)    Maturity. As provided therein, the entire unpaid principal amount of each tranche of the Series B Notes shall be due and payable on the stated maturity date thereof.

(y)    Optional and Contingent Prepayments. As provided in Section 8.2 of the Agreement.

F.    Purchaser Representations. Each Series B Purchaser represents and warrants that the representations and warranties set forth in Section 6 of the Agreement are true and correct on the Series B Execution Date with respect to the purchase of the Series B Notes by such Series B Purchaser with the same force and effect as if each reference to “Series A Notes” set forth therein was modified to refer the “Series B Notes” and each reference to “Initial Purchaser” set forth therein was modified to refer the “Series B Purchaser”.

G. Definition of “Priority Debt”. The definition of the term “Priority Debt” as set forth in Schedule B to the Agreement is deemed to be supplemented and modified to read in its entirety as follows:

“Priority Debt” means, without duplication, (a) any Debt of the Company or a Subsidiary secured by a Lien created or incurred within the limitations of Section 10.3(d) and (b) any Debt of the Company’s Subsidiaries; provided that there shall be excluded from any calculation of Priority Debt, (i) the Debt of any Subsidiary owing to the Company or a Wholly‑owned Significant Subsidiary of the Company, and (ii) the Debt of

any Person which becomes a Subsidiary after the date of the First Initial Closing and any extension, renewal or refunding thereof; provided that such Debt was not incurred in contemplation of such Person becoming a Subsidiary.

H.    Series B Notes Issued under and Pursuant to Agreement. Except as otherwise specifically provided above (and expressly permitted by the Agreement), all of the provisions of the Agreement are incorporated by reference herein and shall apply to the Series B Notes as if expressly set forth in this Supplement. Accordingly, the Series B Notes shall be deemed to be issued under, to be subject to and to have the benefit of all of the terms and provisions of the Agreement as the same may from time to time be amended and supplemented in the manner provided therein.

The execution hereof by the Series B Purchasers shall constitute a contract among the Company and the Series B Purchasers for the uses and purposes hereinabove set forth. By their acceptance hereof, each of the Series B Purchasers shall also be deemed to have accepted and agreed to the terms and provisions of the Agreement, as in effect on the date hereof.

AEP Transmission Company, LLC

By: /s/ Renee V. Hawkins

Name: Renee V. Hawkins

Title: Assistant Treasurer

The Company represents and warrants to each Series B Purchaser that except as hereinafter set forth in this Exhibit A, each of the representations and warranties set forth in Section 5 of the Agreement is true and correct as of the date hereof with respect to the Series B Notes with the same force and effect as if each reference to “Series A Notes” set forth therein was modified to refer to the “Series B Notes” and each reference to “this Agreement” therein was modified to refer to the Agreement as supplemented by this Supplement. The Section references hereinafter set forth correspond to the similar sections of the Agreement which are supplemented hereby:

1.Section 5.3 of the Agreement is deemed to be supplemented and modified to read in its entirety as follows:

“The Company, through its agents, Barclays Capital Inc. and Credit Suisse Securities (USA) LLC, has delivered to each Purchaser a copy of a Private Placement Memorandum, dated October 2013 (the “Memorandum”), relating to the transactions contemplated hereby. The Memorandum fairly describes, in all material respects, the general nature of the business and principal properties of the Company and its Subsidiaries. This Agreement, the Memorandum and the documents, certificates or other writings delivered to the Purchasers by or on behalf of the Company in connection with the transactions contemplated hereby and identified in Schedule 5.3, and the financial statements listed in Schedule 5.5 (this Agreement, the Memorandum and such documents, certificates or other writings and such financial statements delivered to each Purchaser prior to October 17, 2013 being referred to, collectively, as the “Disclosure Documents”), taken as a whole, do not contain any untrue statement of a material fact or omit to state any material fact necessary to make the statements therein not misleading in light of the circumstances under which they were made; provided, that no representation is hereby made with respect to the projections contained therein other than that such projections are based on information that the Company believes to be accurate and were calculated in a manner that the Company believes to be reasonable. Since [December 31, 2012], there has been no change in the financial condition, operations, business or properties of the Company except changes that individually or in the aggregate would not reasonably be expected to have a Material Adverse Effect. There is no fact known to the Company that would reasonably be expected to have a Material Adverse Effect that has not been set forth herein or in the Disclosure Documents.”

2.Section 5.12(b) of the Agreement is deemed to be modified so that each reference to the date “January 1, 2012” is deleted and replaced with a reference to the date “January 1, 2013”.

3.Section 5.15(a) of the Agreement is deemed to be supplemented and modified to read in its entirety as follows:

“(a) Schedule 5.15 sets forth a complete and correct list of all outstanding Debt of the Company and its Subsidiaries as of November 5, 2013 (including a description of the obligors and obligees, principal amount outstanding and collateral therefor, if any, and Guaranty thereof, if any), since which date there has been no Material change in the amounts, interest rates, sinking funds, installment payments or maturities of the Debt of the Company or its Subsidiaries. Neither the Company nor any Subsidiary is in default and no waiver of default is currently in effect, in the payment of any principal or interest on any Debt of the Company or such Subsidiary, the outstanding principal amount of which exceeds $1,000,000, and no event or condition exists with respect to any Debt of the Company or any Subsidiary that would permit (or that with notice or the lapse of time, or both, would permit) one or more Persons to cause such Debt to become due and payable before its stated maturity or before its regularly scheduled dates of payment. Annex A to be attached hereto on the date of the Second Series B Closing will correctly describe all outstanding Debt and any Liens securing such Debt of the Company and its Subsidiaries as of the date of the Second Series B Closing. Since the First Series B Closing, there shall have been no Material increase in the amounts, interest rates, sinking funds, installment payments or maturities of the Debt of the Company or its Subsidiaries listed on Schedule 5.15 (other than the inclusion of the Series B Tranche A Notes, the Series B Tranche B Notes, the Series B Tranche C Notes and the Series B Tranche D Notes). Annex B to be attached hereto on the date of the Third Series B Closing will correctly describe all outstanding Debt and any Liens securing such Debt of the Company and its Subsidiaries as of the date of the Third Series B Closing. Since the Second Series B Closing, there shall have been no Material increase in the amounts, interest rates, sinking funds, installment payments or maturities of the Debt of the Company or its Subsidiaries listed on Schedule 5.15 (other than the inclusion of the Series B Tranche E Notes).”

4.Each of Schedules 5.3, 5.4, 5.5, 5.12 and 5.15 to the Agreement is deemed to be replaced by Schedules 5.3, 5.4, 5.5, 5.12 and 5.15 to this Supplement, as applicable.

5.Each of Annexes A and B to the Agreement is deemed to be replaced by Annexes A and B to this Supplement, as applicable.    

List of Subsidiary Companies: each 100% owned

AEP Appalachian Transmission Company, Inc.

AEP Indiana Michigan Transmission Company, Inc.

AEP Kentucky Transmission Company, Inc.

AEP Ohio Transmission Company, Inc.

AEP Oklahoma Transmission Company, Inc.

AEP Southwestern Transmission Company, Inc.

AEP West Virginia Transmission Company, Inc.

AEP Transmission Company and Subsidiaries 2011 Annual Report Unaudited Consolidated Financial Statements

AEP Transmission Company and Subsidiaries 2012 Annual Report Audited Consolidated Financial Statements

AEP Transmission Company and Subsidiaries 2013 First Quarter and Second Quarter Reports Unaudited Consolidated Financial Statements

For the American Electric Power System Retirement Plan, which is a pension plan within the meaning of section 3(2) of ERISA (other than a Multiemployer Plan) that is subject to the funding requirements of section 302 of ERISA or section 412 of the Code, the adjusted funding target attainment percentage as of January 1, 2013, as most recently certified by the Plan’s actuary on the basis of the actuarial assumptions specified for funding purposes in such Plan’s actuarial valuation report for the plan year beginning January 1, 2013, is 116.77%.

AEP Ohio Transmission Company, Inc (as obligor) $100,000,000 Daily Variable Rate Notes, Series A, due to AEP Transmission Company, LLC (as obligee) on May 16, 2014

AEP Transmission Company, LLC $104,000,000 3.30% Senior Notes, Series A, Tranche A due October 18, 2022

AEP Transmission Company, LLC $85,000,000 4.00% Senior Notes, Series A, Tranche B due October 18, 2032

AEP Transmission Company, LLC $61,000,000 4.73% Senior Notes, Series A, Tranche C due October 18, 2042

AEP Transmission Company, LLC $75,000,000 4.78% Senior Notes, Series A, Tranche D due December 14, 2042

AEP Transmission Company, LLC $25,000,000 4.83% Senior Notes, Series A, Tranche E due March 18, 2043

AEP Ohio Transmission Company, Inc. $83,200,000 3.30% Senior Notes, Series A, Tranche A due October 18, 2022

AEP Ohio Transmission Company, Inc. $68,000,000 4.00% Senior Notes, Series A, Tranche B due October 18, 2032

AEP Ohio Transmission Company, Inc. $48,800,000 4.73% Senior Notes, Series A, Tranche C due October 18, 2042

AEP Ohio Transmission Company, Inc. $10,000,000 4.83% Senior Notes, Series A, Tranche E due March 18, 2043

AEP Indiana Michigan Transmission Company, Inc. $20,800,000 3.30% Senior Notes, Series A, Tranche A due October 18, 2022

AEP Indiana Michigan Transmission Company, Inc. $17,000,000 4.00% Senior Notes, Series A, Tranche B due October 18, 2032

AEP Indiana Michigan Transmission Company, Inc. $12,200,000 4.73% Senior Notes, Series A, Tranche C due October 18, 2042

AEP Indiana Michigan Transmission Company, Inc. $7,500,000 4.83% Senior Notes, Series A, Tranche E due March 18, 2043

AEP Oklahoma Transmission Company, Inc. $75,000,000 4.78% Senior Notes, Series A, Tranche D due December 14, 2042

AEP Oklahoma Transmission Company, Inc. $7,500,000 4.83% Senior Notes, Series A, Tranche E due March 18, 2043