Corporate Office Properties Trust Acquires $16.5 Million York Road Office Building in Hunt Valley, Maryland.

Business Editors

COLUMBIA, Md.--(BUSINESS WIRE)--April 15, 2004

Corporate Office Properties Trust (NYSE:OFC) announced today the acquisition of 10150 York Road, a 178,764 square foot office building located in Hunt Valley, Maryland for $16.5 million. This five-story building was constructed in 1985 as the headquarters for AAI Corporation and is located within two miles of the Company's Deereco Road and Atrium buildings. The building is 77% leased to three tenants presenting a value add opportunity for the Company. The acquisition was financed with proceeds from the Company's Revolving Line of Credit.

"With this acquisition the Company has closed on $90 million of properties, well on our way to the stated acquisition goal of $100 million net of sales for 2004," stated Randall M. Griffin, President and Chief Operating Officer of Corporate Office Properties Trust. "This property represents an outstanding value added opportunity for us with an asset that is well located in the market and in close proximity to our two existing buildings in the market," he added.

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 130 office properties, including one property owned through a joint venture, totaling 10.8 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, 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.