Corporate Office Properties Trust Signs 104,000 Square Foot Lease with Northrop Grumman.

COLUMBIA, Md. -- Corporate Office Properties Trust (NYSE:OFC) announced today that it has executed a long term lease with Northrop Grumman Corporation (NYSE:NOC) for the entire building at 2691 Technology Drive, Annapolis Junction, Maryland. The building known as 191 NBP is a 104,000 square foot Class A office building currently under construction in Phase I of The National Business Park (NBP).

NBP Phase I has twelve buildings totaling 1.3 million square feet of space in operation that are 100% leased. 191 NBP, along with one other building (220 NBP) that will become operational in September, will complete NBP Phase I at 1.5 million square feet. Phase II at The National Business Park will consist of an additional 10 buildings totaling 1.3 million square feet. The first two buildings of Phase II are currently under construction.

"We continue to experience strong demand for The National Business Park and are particularly pleased to be able to accommodate, on a timely basis, one of our key tenant's requirements," stated Randall M. Griffin, President and Chief Operating Officer for Corporate Office Properties Trust.

Company Information

Corporate Office Properties Trust is a fully integrated, self-managed, real estate investment trust which focuses on the ownership, management, leasing, acquisition and development of suburban office properties located in select Mid-Atlantic submarkets. The Company currently owns 132 office properties, including two properties held through joint ventures, totaling 10.9 million rentable square feet. Corporate Development Services provides a wide range of development and construction management services. In addition, Corporate Office Services provides land planning, design/build services, and consulting and merchant development to third party entities. 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;

--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 our filings with the Securities and Exchange Commission, particularly the section entitled "Risk Factors" in Item 1 of our Annual Report on Form 10-K for the year ended December 31, 2003.