EXHIBIT 99.1

THIRTIETH AMENDMENT

TO

SECOND AMENDED AND RESTATED

LIMITED PARTNERSHIP AGREEMENT

OF

CORPORATE OFFICE PROPERTIES, L.P.

This Thirtieth Amendment (the “Amendment”) to the Second Amended and Restated Limited Partnership Agreement Of Corporate Office Properties, L.P., a Delaware limited partnership (the Partnership), is made and entered into as of July 16, 2013, by the undersigned.

Recitals

A.    The Partnership is a limited partnership organized under the Delaware Revised Uniform Limited Partnership Act and governed by that certain Second Amended and Restated Limited Partnership Agreement dated as of December 7, 1999, as amended to the date hereof (as amended, the “Partnership Agreement”).

B.    The sole general partner of the Partnership is Corporate Office Properties Trust, a real estate investment trust formed under the laws of the State of Maryland (the “General Partner”).

C.    Pursuant to Section 11.1 (b) (iii), the General Partner desires to amend the Partnership Agreement to reflect the admission, substitution, termination and/or withdrawal of various limited partners in accordance with the terms of the Partnership Agreement.

NOW THEREFORE, the General Partner, intending to be legally bound, hereby amends the Partnership Agreement as follows, effective as of the date first set forth above.

1.

Exhibit 1, Schedule of Partners, as attached hereto and by this reference made a part hereof, is hereby substituted for and intended to replace any prior Exhibit 1 attached to a prior Amendment to the Partnership Agreement, and as attached hereto shall be a full and complete listing of all the general and limited partners of the Partnership as of the date of this Amendment, same being intended and hereby superceding all prior Exhibit 1 listings.

In Witness Whereof, the General Partner has executed this Amendment as of the day and year first above written.

Corporate Office Properties Trust, a

Maryland Real Estate Investment Trust

By:     /s/ Roger A. Waesche, Jr.

Roger A. Waesche, Jr.

President & Chief Executive Officer

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Exhibit 1 Addendum--30th Amendment
Schedule of Partners
General Partner		Common Units of Partnership Units			Series H Preferred Units			Series I Preferred Units			Series K Preferred Units			Series L Preferred Units
Corporate Office Properties Trust		87,355,403			2,000,000						531,667			6,900,000
Limited Partners and Preferred Limited Partners
Jay H. Shidler		431,893
Shidler Equities, L.P.		1,353,963
Clay W. Hamlin, III		63,244
LBCW Limited Partnership		841,107
Robert L. Denton		329,000
James K. Davis		51,589
Samuel Tang		4,389
Lawrence J. Taff		13,733
M.O.R. 44 Gateway Associates Limited Partnership		1
John Parsinen		49,434
M.O.R. Commons Limited Partnership		7
Lynn Hamlin		121,411
Housing Affiliates, Inc.		4,402
Reingle Corp.		730
Joseph Tawil		2,160
The Lovejoy Trust		59,528
The Century Trust		59,528
A. Charles Wilson, Trustee of the A. Charles Wilson and Betty S. Wilson Trust u/d/t June 18, 1980--Survivor's Trust		5,908
Irwin Hoffman		1,880
The Rouse Family Exemption Trust		2,160
Lawrence G. Rief		2,526
David D. Jenkins		262,165
RA & DM, Inc.		2,954
Richard Alter		43,817
Donald Manekin		23,336
William Winstead		14,019
Richard Manekin		8,988
Robert Manekin		8,988
Charles Manekin		3,899
Francine Manekin		880
Sandye Sirota		5,427
Lynn Stern		880
Louis LaPenna		2,513
Jamie Deutsch		22
Kelly Alter		22
Bryn Mawr Presbyterian Church		150
The Nichols School		1,870
TRC Associates Limited Partnership								352,000
TOTAL		91,133,926			2,000,000			352,000			531,667			6,900,000