Corporate Office Properties Trust Signs 125,568 Square Foot Lease at the National Business Park.

COLUMBIA, Md. -- Corporate Office Properties Trust (NYSE:OFC) announced today the execution of a long-term lease with one of its Top 20 tenants for the entire building to be located at 322 Sentinel Drive, Annapolis Junction, Maryland. The building, to be known as 322 NBP, will be a 125,568 square foot Class A office building and is one of three buildings under construction in Phase II of The National Business Park (NBP).

Phase II at NBP when complete, will consist of 10 buildings totaling 1.3 million square feet. Including 322 NBP, Corporate Office Properties Trust has 445,212 square feet under construction in Phase II at NBP. 322 NBP has a planned occupancy of fourth quarter 2006. Phase I consisted of 1.5 million square feet and is 100% leased.

"We are pleased to announce another full building lease at NBP, and to announce that this lease is with one of our existing tenants," stated Randall M. Griffin, President and Chief Executive Officer for Corporate Office Properties Trust. "The Company continues to focus on delivering exceptional tenant service, therefore maintaining quality relationships with its tenants, he stated."

Company Information

Corporate Office Properties Trust (COPT) is a fully integrated, self-managed real estate investment trust (REIT) that focuses on the ownership, management, leasing, acquisition and development of suburban office properties primarily in select Mid-Atlantic submarkets. The Company is among the largest owners of suburban office properties in the Greater Washington, DC region. The Company currently owns 160 office properties totaling 13.4 million rentable square feet, which includes 18 properties totaling 885,000 square feet held through joint ventures. The Company has implemented a core customer expansion strategy that is built around meeting, through acquisitions and development, the multi-location requirements of the Company's existing strategic tenants. The Company's property management services team provides comprehensive property and asset management to company owned properties and select third party clients. The Company's development and construction services team provides a wide range of development and construction management services for company owned properties, as well as land planning, design/build services, consulting, and merchant development to select third party clients. The Company's shares are traded on the New York Stock Exchange under the symbol OFC. More information on Corporate Office Properties Trust can be found on the Internet at www.copt.com.

Forward-Looking Information

This press release may contain "forward-looking" statements, as defined in Section 27A of the Securities Act of 1933 and Section 21E of the Securities Exchange Act of 1934, that are based on the Company's current expectations, estimates and projections about future events and financial trends affecting the Company. Forward-looking statements can be identified by the use of words such as "may", "will", "should", "expect", "estimate" or other comparable terminology. Forward-looking statements are inherently subject to risks and uncertainties, many of which the Company cannot predict with accuracy and some of which the Company might not even anticipate. Accordingly, the Company can give no assurance that these expectations, estimates and projections will be achieved. Future events and actual results may differ materially from those discussed in the forward-looking statements.

Important factors that may affect these expectations, estimates, and projections include, but are not limited to:

--the Company's ability to borrow on favorable terms;

--general economic and business conditions, which will, among other things, affect office property demand and rents, tenant creditworthiness, interest rates and financing availability;

--adverse changes in the real estate markets including, among other things, increased competition with other companies;

--risk of real estate acquisition and development, including, among other things, risks that development projects may not be completed on schedule, that tenants may not take occupancy or pay rent or that development or operating costs may be greater than anticipated;

--risks of investing through joint venture structures, including risks that the Company's joint venture partners may not fulfill their financial obligations as investors or may take actions that are inconsistent with the Company's objectives;

--our ability to satisfy and operate effectively under federal income tax rules relating to real estate investment trusts and partnerships;

--governmental actions and initiatives; and

--environmental requirements.

The Company undertakes no obligation to update or supplement any forward-looking statements. For further information, please refer to the Company's filings with the Securities and Exchange Commission, particularly the section entitled "Risk Factors" in Item 1 of the Company's Annual Report on Form 10-K for the year ended December 31, 2004.