Corporate Office Properties Trust Closes on Three Office Buildings for $40.5 Million in Colorado Springs and San Antonio.

COLUMBIA, Md. -- Corporate Office Properties Trust (COPT) (NYSE:OFC) announced today the acquisition of three office buildings, one in Colorado Springs, Colorado and two in San Antonio, Texas. The first property in Colorado Springs, Colorado was acquired for $23.2 million, and is a three story Class A office building containing 124,305 square feet, located at 3535 Northrop Grumman Point. The office building is located in the Colorado Springs Airport Business Park, known as Cresterra. COPT was selected as master developer of Cresterra in September 2007. Cresterra is situated at the entrance of the Colorado Springs Airport and adjacent to the Peterson Air Force Base. The building is 100% leased, long-term, to Northrop Grumman Corporation and is the location of their Colorado Springs headquarters.

The Company's Colorado Springs portfolio now consists of 15 office buildings with 1.0 million square feet, 3 office buildings under construction with 232,000 square feet, 2 office buildings under development with 235,000 square feet and 192 acres of land that can support approximately 2.5 million square feet of development. The office portfolio is 96.7% leased.

The other two properties in San Antonio, Texas, known collectively as 151 Technology Center, were acquired for $17.3 million, and are two story office buildings containing a total of 122,975 square feet, located at 1560 Cable Ranch Road. The office buildings are located in the Northwest submarket, near the interchange of Loop 410 and Highway 151, in close proximity to COPT's other San Antonio properties. The buildings are 100% leased, long-term, to Sears, Air Force Federal Credit Union and AFNI.

The Company's San Antonio portfolio now consists of 4 office buildings with 601,000 square feet, 2 office buildings under construction with 91,000 square feet and 58 acres of land that can support approximately 725,000 square feet of development. The office portfolio is 100% leased.

"We are pleased to add to our strong position in Colorado Springs and to reinforce our commitment in San Antonio," stated Randall M. Griffin, President and Chief Executive Officer for Corporate Office Properties Trust. "These acquisitions provide COPT with continued growth opportunities in both markets and fit naturally into our strategy of owning core buildings in the defense information technology sector in areas near government demand drivers," he added.

Company Information

Corporate Office Properties Trust (COPT) (NYSE:OFC) is a specialty office real estate investment trust (REIT) that focuses on strategic customer relationships and specialized tenant requirements in the U.S. Government, Defense Information Technology and Data sectors. The Company acquires, develops, manages and leases properties which are typically concentrated in large office parks primarily located adjacent to government demand drivers and/or in growth corridors. As of March 31, 2008, the Company owned 248 office and data properties totaling 18.7 million rentable square feet, which includes 18 properties totaling 806,000 square feet held through joint ventures. The Company's portfolio primarily consists of technically sophisticated buildings in visually appealing settings that are environmentally sensitive, sustainable and meet unique customer requirements. More information on COPT can be found 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, 2007.