Limited Partnership Agreement

Corporate Office Properties, L.P.

This Fifteenth 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 January 31, 2004, 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 (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.
		Executive Vice President

SCHEDULE OF PARTNERS

General Partner		Partnership Units
Corporate Office Properties Trust		27,291,612

Limited Partners and Preferred Limited Partners
Jay H. Shidler		452,878
Shidler Equities, L.P.		2,995,439
Clay W. Hamlin, III		566,492
LBCW Limited Partnership		3,161,427
Robert L. Denton		434,910
James K. Davis		51,589
John E. De B. Blockey, Trustee of the John E. de B. Blockey Living Trust dated 9/12/88		300,625
Frederick K. Ito Trust		29,140
June Y. I. Ito Trust		29,135
RP Investments, LLC		268,671
Denise J. Liszewski		34,333
Samuel Tang		22,889
Laswrence J. Taff		13,733
Kimberly F. Acquino		5,874
M.O.R. XXIX Associates Limited Partnership		148,381
M.O.R. 44 Gateway Associates Limited Partnership		1
John Parsinen		90,000
M.O.R. Commons Limited Partnership		7
John Edward De Burgh Blockey and Sandar Juanita Blockey		50,476
Anthony Muscatello		90,905
Lynn Hamlin		121,411
National Prostrate Cancer Coalition		500
Wildlands Conservancy		250
National Aquarium in Baltimore		300
University of Pennsylvania - Frineds of Penn Tennis		150
John Hopkins University		300
Nichols School		500
		36,161,928

Exhibit 1 Addendum

Series Preferred Units	Preferred Limited Partner	No. of Preferred Units	Liquidation Preference Per Preferred Unit		Priority Percentage Return *		Priority	Conversion Factor		Conversion Commencement Date

B	General Partner	1,250,000	$	25	2.50	%	Senior	None		N/A
D	General Partner	544,000	$	25	1.00	%	Senior		**		**
E	General Partner	1,150,000	$	25	2.5625	%	Senior	None		N/A
F	General Partner	1,425,000	$	25	10.25	%	Senior	None		N/A
G	General Partner	2,200,000	$	25	8	%	Senior	None		N/A
H	General Partner	2,000,000	$	25	7.5	%	Senior	None		N/A

* Priority Return Percentage is expressed as a percentage of the Liquidation Preference per Distribution Period. See the Agreement for the definitions of “Priority Return Percentage,” “Liquidation Preference” and “Distribution Period.”

** With respect to any series of Preferred Units issued to the General Partner pursuant to Section 4.2(B) of the Agreement, the Conversion Commencement Date and the applicable Conversion Factor shall correspond to the conversion commencement date and conversion factor of the related issuance of securities by the General Partner as provided in Section 4.2(B) of the Agreement. See Section 9.8(A)(1) of the Agreement.