CORPORATE OFFICE PROPERTIES TRUST Common Shares of Beneficial Interest AMENDMENT TO SALES AGREEMENT

“Prospectus Supplement” means (a) prior to March 26, 2015, the prospectus supplement specifically relating to the Stock prepared and filed with the Commission pursuant to Rule 424(b) on October 31, 2012, and (b) on or after March 26, 2015, the prospectus supplement specifically relating to the Stock prepared and filed with the Commission pursuant to 424(b) in the form most recently filed by the Company with the Commission; and

(d)                                 The following is added to the Sales Agreement as Section 1(vv):

Neither the Company nor any of its Subsidiaries nor, to the knowledge of the Company, any director, officer, or employee of the Company or any of its Subsidiaries nor, to the knowledge of the Company, any agent, affiliate or other person acting on behalf of the Company or any of its Subsidiaries has (i) used any funds for any unlawful contribution, gift, entertainment or other unlawful expense relating to political activity; (ii) made or taken an act in furtherance of an offer, promise or authorization of any direct or indirect unlawful payment or benefit to any foreign or domestic government or regulatory official or employee, including of any government-owned or controlled entity or of a public international organization, or any person acting in an official capacity for or on behalf of any of the foregoing, or any political party or party official or candidate for political office; (iii) violated or is in violation of any provision of the Foreign Corrupt Practices Act of 1977, as amended, or any applicable law or regulation implementing the OECD Convention on Combating Bribery of Foreign Public Officials in International Business Transactions, or committed an offence under the Bribery Act 2010 of the United Kingdom, or any other applicable anti-bribery or anti-corruption laws; or (iv) made, offered, agreed, requested or taken an act in furtherance of any unlawful bribe or other unlawful benefit, including, without limitation, any rebate, payoff, influence payment, kickback or other unlawful or improper payment or benefit.  The Company and its Subsidiaries have instituted, maintain and enforce, and will continue to maintain and enforce policies and procedures designed to promote and ensure compliance with all applicable anti-bribery and anti-corruption laws.

(e)                                  The first sentence of Section 5(a) of the Sales Agreement is hereby deleted and replaced in its entirety with the following:

The Prospectus Supplement shall have been filed with the Commission pursuant to Rule 424(b) and the Company shall have complied with all other requirements applicable to the Prospectus or any supplement thereto under Rule 424(b) (without giving effect to Rule 424(b)(8).

(f)                                   Schedules I, II, III and IV to the Sales Agreement are hereby deleted and replaced in their entirety with Schedules I, II, III and IV to this Amendment, respectively.

2.                                      No Other Amendments.  Except as specifically set forth herein, all other provisions of the Sales Agreement shall remain in full force and effect.

3.                                      Governing Law.  This Amendment shall be governed by and construed in accordance with the laws of the State of New York.

4.                                      Waiver of Jury Trial.  The Company and the Agent hereby irrevocably waive, to the fullest extent permitted by applicable law, any and all right to trial by jury in any legal proceeding arising out of or relating to this Amendment or the transactions contemplated hereby.

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5.                                      Counterparts.  This Amendment may be executed in one or more counterparts and, if executed in more than one counterpart, the executed counterparts shall each be deemed to be an original but all such counterparts shall together constitute one and the same instrument.

6.                                      Headings.  The headings herein are inserted for convenience of reference only and are not intended to be part of, or to affect the meaning or interpretation of, this Amendment.

[Signature Pages Follow]

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If the foregoing correctly sets forth the agreement between the Company, the Operating Partnership and the Agent, please indicate your acceptance in the space provided for that purpose below.

[Amendment to Sales Agreement]

[Amendment to Sales Agreement]

SCHEDULE I

SUBSIDIARIES

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SCHEDULE II

SIGNIFICANT SUBSIDIARIES - MLB OPINION

Corporate Development Services, LLC

Corporate Office Management, Inc.

Corporate Office Properties, L.P.

COPT Property Management Services, LLC

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SCHEDULE III

SIGNIFICANT SUBSIDIARIES — GENERAL COUNSEL OPINION

Airport Square II, LLC

Blue Bell Investment Company, L.P.

Corporate Gatespring, LLC

NBP One, LLC

NBP 131, LLC

NBP 135, LLC

7200 Riverwood, LLC

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SCHEDULE IV

MATERIAL DOCUMENTS

Second Amended and Restated Limited Partnership Agreement of the Operating Partnership, dated December 7, 1999 (filed with the Company’s Annual Report on Form 10-K on March 16, 2000).

First Amendment to Second Amended and Restated Limited Partnership Agreement of the Operating Partnership, dated December 21, 1999 (filed with the Company’s Annual Report on Form 10-K on March 16, 2000).

Second Amendment to Second Amended and Restated Limited Partnership Agreement of the Operating Partnership, dated December 21, 1999 (filed with the Company’s Post Effective Amendment No. 2 to Form S-3, dated November 1, 2000 (Registration Statement No. 333-71807)).

Third Amendment to Second Amended and Restated Limited Partnership Agreement of the Operating Partnership, dated September 29, 2000 (filed with the Company’s Post Effective Amendment No. 2 to Form S-3, dated November 1, 2000 (Registration Statement No. 333-71807)).

Fourth Amendment to Second Amended and Restated Limited Partnership Agreement of the Operating Partnership, dated November 27, 2000 (filed with the Company’s Annual Report on Form 10-K on March 27, 2003).

Fifth Amendment to Second Amended and Restated Limited Partnership Agreement of the Operating Partnership, dated January 25, 2001 (filed with the Company’s Annual Report on Form 10-K on March 27, 2003).

Sixth Amendment to Second Amended and Restated Limited Partnership Agreement of the Operating Partnership, dated April 3, 2001 (filed with the Company’s Current Report on Form 8-K, dated April 4, 2001).

Seventh Amendment to Second Amended and Restated Limited Partnership Agreement of Operating Partnership, dated August 30, 2001 (filed with the Company’s Annual Report on Form 10-K on March 27, 2003).

Eighth Amendment to Second Amended and Restated Limited Partnership Agreement of Operating Partnership, dated September 14, 2001 (filed with the Company’s Amended Current Report on Form 8-K dated September 14, 2001).

Ninth Amendment to Second Amended and Restated Limited Partnership Agreement of Operating Partnership, dated October 6, 2001 (filed with the Company’s Annual Report on Form 10-K on March 27, 2003).

Tenth Amendment to Second Amended and Restated Limited Partnership Agreement of Operating Partnership, dated December 29, 2001 (filed with the Company’s Annual Report on Form 10-K on March 27, 2003).

Eleventh Amendment to Second Amended and Restated Limited Partnership Agreement of Operating Partnership, dated December 15, 2002 (filed with the Company’s Annual Report on Form 10-K on March 27, 2003).

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Twelfth Amendment to Second Amended and Restated Limited Partnership Agreement of Operating Partnership, dated as of June 2, 2003 (filed with the Company’s Quarterly Report on Form 10-Q on August 12, 2003).

Thirteenth Amendment to Second Amended and Restated Limited Partnership Agreement of Operating Partnership, dated as of August 11, 2003 (filed with the Company’s Quarterly Report on Form 10-Q on November 12, 2003).

Fourteenth Amendment to Second Amended and Restated Limited Partnership Agreement of Operating Partnership, dated as of December 18, 2003 (filed with the Company’s Annual Report on Form 10-K on March 11, 2004).

Fifteenth Amendment to Second Amended and Restated Limited Partnership Agreement of Operating Partnership, dated as of January 31, 2004 (filed with the Company’s Annual Report on Form 10-K on March 11, 2004).

Sixteenth Amendment to Second Amended and Restated Limited Partnership Agreement of Operating Partnership, dated April 15, 2004 (filed with the Company’s Quarterly Report on Form 10-Q on May 7, 2004).

Seventeenth Amendment to Second Amended and Restated Limited Partnership Agreement of Operating Partnership, dated September 23, 2004 (filed with the Company’s Current Report on Form 8-K dated September 23, 2004).

Eighteenth Amendment to Second Amended and Restated Limited Partnership Agreement of Operating Partnership, dated April 18, 2005  (filed with the Company’s Current Report on Form 8-K dated April 22, 2005).

Nineteenth Amendment to Second Amended and Restated Limited Partnership Agreement of Operating Partnership, dated July 8, 2005 (filed with the Company’s Current Report on Form 8-K dated July 14, 2005).

Twentieth Amendment  to  Second  Amended  and Restated Limited Partnership Agreement  of  Operating  Partnership,  dated June 29, 2006 (filed with the Company’s Current Report on Form 8-K, dated July 6, 2006).

Twenty-First Amendment to Second Amended and Restated Limited Partnership Agreement of Operating Partnership, dated July 20, 2006 (filed with the Company’s Current Report on Form 8-K, dated July 26, 2006).

Twenty-Second Amendment to Second Amended and Restated Limited Partnership Agreement of Operating Partnership, dated January 9, 2007 (filed with the Company’s Current Report on Form 8-K, dated January 16, 2007).

Twenty-Third Amendment to Second Amended and Restated Limited Partnership Agreement of Operating Partnership, dated April 6, 2007 (filed with the Company’s Current Report on Form 8-K, dated April 12, 2007).

Twenty-Fourth Amendment to Second Amended and Restated Limited Partnership Agreement of Operating Partnership, dated November 2, 2007 (filed with the Company’s Current Report on Form 8-K, dated November 5, 2007).

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Twenty-Fifth Amendment to Second Amended and Restated Limited Partnership Agreement of Operating Partnership, dated December 31, 2008 (filed with the Company’s Current Report on Form 8-K, dated January 5, 2009).

Twenty-Sixth Amendment to Second Amended and Restated Limited Partnership Agreement of Operating Partnership., dated March 4, 2010 (filed with the Company’s Current Report on Form 8-K dated March 10, 2010).

Twenty-Seventh Amendment to Second Amended and Restated Limited Partnership Agreement of Corporate Office Properties, L.P., dated February 3, 2011 (filed with the Company’s Current Report on Form 8-K dated February 9, 2010).

Twenty-Eighth Amendment to Second Amended and Restated Limited Partnership Agreement of Corporate Office Properties, L.P., dated September 15, 2011 (filed with the Company’s Current Report on Form 8-K dated September 16, 2011).

Twenty-Ninth Amendment to Second Amended and Restated Limited Partnership Agreement of Corporate Office Properties, L.P. dated June 27, 2012 (filed with the Company’s Current Report on Form 8-K dated June 27, 2012).

Thirtieth Amendment to Second Amended and Restated Limited Partnership Agreement of Corporate Office Properties, L.P. dated July 16, 2013 (filed with the Company’s Current Report on Form 8-K dated July 19, 2013).

Thirty-First Amendment to Second Amended and Restated Limited Partnership Agreement of Corporate Office Properties, L.P. dated September 17, 2013 (filed with the Company’s Current Report on Form 8-K dated September 19, 2013).

Amended and Restated Registration Rights Agreement, dated March 16, 1998, for the benefit of certain shareholders of the Company (filed with the Company’s Quarterly Report on Form 10-Q on August 12, 1998).

Registration Rights Agreement, dated September 28, 1998, for the benefit of certain shareholders of the Company.

Registration Rights Agreement, dated January 25, 2001, for the benefit of Barony Trust Limited (filed with the Company’s Annual Report on Form 10-K on March 22, 2001).

Registration Rights Agreement, dated September 18, 2006, among the Operating Partnership, the Company, Banc of America Securities LLC and J.P. Morgan Securities Inc. (filed with the Company’s Current Report on Form 8-K dated September 22, 2006).

Registration Rights Agreement, dated April 7, 2010, among the Operating Partnership, the Company, J.P. Morgan Securities Inc. and RBC Capital Markets Corporation (filed with the Company’s Current Report on Form 8-K dated April 16, 2010).

Registration Rights Agreement, dated May 6, 2013, among the Operating Partnership, the Company, J.P. Morgan Securities LLC and Wells Fargo Securities LLC (filed with the Company’s Current Report on Form 8-K dated May 7, 2013).

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Indenture, dated as of September 18, 2006, among the Operating Partnership, as issuer, the Company, as guarantor, and Wells Fargo Bank, National Association, as trustee (filed with the Company’s Current Report on Form 8-K dated September 22, 2006).

3.50% Exchangeable Senior Notes due 2026 of the Operating Partnership (filed with the Company’s Current Report on Form 8-K dated September 22, 2006).

Indenture, dated as of April 7, 2010, among the Operating Partnership, as issuer, the Company, as guarantor, and Wells Fargo Bank, National Association, as trustee (filed with the Company’s Current Report on Form 8-K dated April 16, 2010).

4.25% Exchangeable Senior Notes due 2030 of the Operating Partnership (filed with the Company’s Current Report on Form 8-K dated April 16, 2010).

Indenture, dated as of May 6, 2013, among the Operating Partnership, as issuer, the Company, as guarantor, and U.S. Bank National Association, as trustee (filed with the Company’s Current Report on Form 8-K dated May 7, 2013).

3.600% Senior Notes due 2023 of the Operating Partnership (filed with the Company’s Current Report on Form 8-K dated May 7, 2013).

Common Stock Delivery Agreement, dated as of September 18, 2006, between the Operating Partnership and Corporate Office Properties Trust (filed with the Company’s Current Report on Form 8-K dated September 22, 2006).

Common Stock Delivery Agreement, dated as of April 7, 2010, between the Company and the Operating Partnership (filed with the Company’s Current Report on Form 8-K dated April 16, 2010).

Credit Agreement, dated as of September 1, 2011, by and among Corporate Office Properties, L.P., Corporate Office Properties Trust, J.P. Morgan Securities LLC, KeyBanc Capital Markets, KeyBank National Association, JPMorgan Chase Bank, N.A., Bank of America, N.A., Royal Bank of Canada, Wells Fargo Bank, National Association, Barclays Bank PLC, PNC Bank, National Association, Regions Bank, Manufacturers and Traders Trust Company and SunTrust Bank (filed with the Company’s Current Report on Form 8-K/A on September 1, 2011).

Term Loan Agreement, dated as of September 1, 2011, by and among Corporate Office Properties, L.P., Corporate Office Properties Trust, J.P. Morgan Securities LLC, KeyBanc Capital Markets, KeyBank National Association, JPMorgan Chase Bank, N.A., Bank of America, N.A., Royal Bank of Canada, Barclays Bank PLC, PNC Bank, National Association, Royal Bank of Canada, Wells Fargo Bank, National Association, Regions Bank, Manufacturers and Traders Trust Company, and SunTrust Bank (filed with the Company’s Current Report on Form 8-K/A on September 1, 2011).

Term Loan Agreement, dated as of February 14, 2012, by and among Corporate Office Properties, L.P., Corporate Office Properties Trust, J.P. Morgan Securities LLC, KeyBanc Capital Markets, KeyBank National Association, JPMorgan Chase Bank, N.A., Bank of America, N.A., PNC Bank, National Association, Royal Bank of Canada and Wells Fargo Bank, National Association (filed with the Company’s Quarterly Report on Form 10-Q on April 27, 2012).

Indenture, dated as of September 16, 2013, by and among Corporate Office Properties, L.P., as issuer, Corporate Office Properties Trust, as guarantor, and U.S. Bank National Association, as trustee (filed with the Company’s Current Report on Form 8-K dated September 19, 2013).

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First Supplemental Indenture, dated September 16, 2013, by and among Corporate Office Properties, L.P., as issuer, Corporate Office Properties Trust, as guarantor, and U.S. Bank National Association, as trustee (filed with Company’s Current Report on Form 8-K dated September 19, 2013).

5.25% Senior Notes due 2024 of the Operating Partnership (filed with the Company’s Current Report on Form 8-K dated September 13, 2013).

Second Supplemental Indenture, dated May 21, 2014, by and among Corporate Office Properties, L.P., as issuer, Corporate Office Properties Trust, as guarantor, and U.S. Bank National Association, as trustee (filed with the Company’s Current Report on Form 8-K dated May 27, 2014).

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