Corporate Office Properties Trust Reports 2009 Year End Results

Shareholder Return

The Company's shareholders earned a total return of 25% for the year 2009. For the past ten years, the Company's shareholders earned a total return of 693%, the second highest ten year return among all equity REITs based on numbers compiled by NAREIT as of December 31, 2009.

2009 Highlights

• 5% increase in Diluted Funds from Operations ("Diluted FFO") per share excluding non-comparable items to $2.49 for the year ended 2009 from $2.38 for 2008. Excluded from 2009 were operating property acquisition costs which under prior accounting rules would have been capitalized. Excluded from 2008 was a gain on early extinguishment of debt upon the repurchase of exchangeable notes. Including these items, we reported 2009 diluted FFO per share of $2.46 and 2008 diluted FFO per share of $2.52.
• 8% decrease in diluted earnings per share ("Diluted EPS") to $.70 for the year ended 2009 as compared to $.76 per diluted share for the year ended 2008.
• 18% increase in diluted Adjusted Funds from Operations ("AFFO") to $117.9 million for the year ended 2009 as compared to $100.1 million for the year ended 2008.
• 63% Diluted FFO payout ratio and 81% Diluted AFFO payout ratio for the year.
• 1.1 million square feet under construction that is 54% leased as of February 5, 2010.
• 759,000 square feet in 10 development properties placed into service for the year.
• 90.7% occupied and 91.3% leased for our wholly-owned portfolio as of December 31, 2009.
• 73% renewal rate on expiring leases for the year, representing approximately 1.8 million square feet renewed with an average capital cost of $7.76 per square foot. Total rent on renewed space increased 4% on a straight-line basis, as measured from the straight-line rent in effect preceding the renewal date and decreased 3% on a cash basis.
• 5% increase in same office property cash NOI for the year, including gross lease termination fees. Excluding gross lease termination fees, same office property cash NOI increased 3% for the year. The Company's same office portfolio for the year ended December 31, 2009 represents 83% of the rentable square feet of its consolidated portfolio and consists of 220 properties.
• 5.4% increase of quarterly common cash dividend in September 2009.

"The Company continued to perform well in 2009 despite a challenging economic environment. We had FFO growth and positive same office results along with opportunistic acquisitions," stated Randall M. Griffin, President and Chief Executive Officer, Corporate Office Properties Trust. "Importantly, our development activity continues to be entirely focused on our super core clients - the U.S. Government and Defense Information Technology tenants. As expected, we are starting to see an acceleration in demand due to BRAC and the Cyber Initiative, which should help position us for an earlier rebound from the impacts of the recession," he stated.

Financial Ratios

As of December 31, 2009, the Company had a total market capitalization of $4.6 billion, with $2.1 billion in debt outstanding, equating to a 45% debt-to-total market capitalization ratio.

As of December 31, 2009, the Company's weighted average interest rate was 5% and the Company had 75% of the total debt subject to fixed interest rates.

For the year 2009, the Company's EBITDA to interest expense coverage ratio was 3.27x, and the EBITDA fixed charge coverage ratio was 2.69x.

Reconciliations of non-GAAP measures to the most directly comparable GAAP measures are included in the tables that follow the text of this press release.

Operating Results

At December 31, 2009, the Company's wholly-owned portfolio of 249 office properties totaled 19.1 million square feet. The weighted average remaining lease term for the portfolio was 4.8 years and the average rental rate (including tenant reimbursements) was $24.63 per square foot.

For the year, 2.2 million square feet was renewed and retenanted. Total straight-line rent for renewed and retenanted space increased 2% and total rent on a cash basis decreased 6%. The average committed cost for renewed and retenanted space was $9.17 per square foot.

For the quarter ended December 31, 2009, 408,000 square feet was renewed equating to a 79% renewal rate, at an average committed cost of $13.12 per square foot. Total rent on renewed space increased 5% on a straight-line basis, as measured from the straight-line rent in effect preceding the renewal date and decreased 4% on a cash basis. For renewed and retenanted space of 509,000 square feet, total straight-line rent increased 3% and total rent on a cash basis decreased 6%. The average committed cost for renewed and retenanted space was $14.14 per square foot.

The Company recognized lease termination fees of $4.6 million, net of write-offs of related straight-line rents and accretion of intangible assets and liabilities for the year ended December 31, 2009, as compared to $481,000 for the year ended December 31, 2008.

Development Activity

At December 31, 2009, the Company had 2.4 million square feet under construction, development and redevelopment for a total projected cost of $476.9 million.

The Company's land inventory (wholly-owned and joint venture) at December 31, 2009 totaled 1,818 acres that can support 16.6 million square feet of development.

Acquisition Activity

For 2009, the Company acquired 697,000 square feet for $172.5 million that included:

• 61,000 square foot building and adjacent land that can support approximately 90,000 square feet of additional development for $12.5 million, located at 12515 Academy Ridge in Colorado Springs, Colorado. The building is 100% leased long term to Real Time Logic, Inc., a wholly owned subsidiary of Integral Systems, Inc.
• 474,000 square foot office tower, a parking lot, a utility distribution center, four waterfront lots and riparian rights for $123.2 million, all part of the Canton Crossing planned unit development in Baltimore, Maryland. The office tower was 90% leased on the date of acquisition.
• 162,000 square foot building and a 0.9 acre adjacent land parcel for $38.0 million, located at 1550 West Nursery Road in Linthicum, Maryland. The building is 100% leased long term to Northrop Grumman Corporation.

Financing and Capital Transactions

The Company executed the following transactions during the year:

• Issued approximately 3.0 million common shares in an underwritten public offering made in conjunction with the Company's inclusion in the S&P MidCap 400 Index on April 1, 2009. The shares were issued at a public offering price of $24.35 per share for net proceeds after underwriting discounts but before offering expenses of $72.1 million. The net proceeds were used to pay down the Company's Revolving Credit Facility and for general corporate purposes.
• Closed on the following borrowings, using the proceeds primarily to repay maturing debt and pay down its Revolving Credit Facility:

• a $23.4 million joint venture construction loan with a two-year term and the right to extend for an additional year that carries interest at LIBOR plus 2.75%.
• a $50.0 million secured loan with a five-year term that carries interest at LIBOR plus 3.0% (subject to a LIBOR floor of 2.5%).
• a $90.0 million secured loan with a five-year term that carries interest at 7.25%.
• a $185.0 million secured loan with a seven-year term that carries interest at 7.25%.

Subsequent Events

The Company executed the following leases subsequent to quarter end.

• 125,000 square foot building located at 324 Sentinel Way in Annapolis Junction, Maryland. The building is 100% leased, long-term.

• 250,000 square feet in 2 buildings located at 8000 and 8030 Potranco Road in San Antonio, Texas. The buildings are 100% leased, long-term.

Conference Call

The Company will hold an investor/analyst conference call:

Conference Call (within the United States)

Date: Thursday, February 11, 2010

Time: 10:00 a.m. Eastern Time

Telephone Number: 888-679-8033

Passcode: 10883637

Conference Call (outside the United States)

Date: Thursday, February 11, 2010

Time: 10:00 a.m. Eastern Time

Telephone Number: 617-213-4846

Passcode: 10883637

Please use the following link to pre-register and view important information about this conference call. Pre-registering is not mandatory but is recommended as it will provide you immediate entry into the call and will facilitate the timely start of the conference. Pre-registration only takes a few moments and you may pre-register at anytime, including up to and after the call start time. To pre-register, please click on the below link:

https://www.theconferencingservice.com/prereg/key.process?key=PXUDU6UW7

You may also pre-register in the Investor Relations section of the Company's website at www.copt.com. Alternatively, you may be placed into the call by an operator by calling the number provided above at least 5 to 10 minutes before the start of the call. A replay of this call will be available beginning Thursday, February 11 at 2:00 p.m. Eastern Time through Thursday, February 25 at midnight Eastern Time. To access the replay within in the United States, please call 888-286-8010 and use passcode 38751918. To access the replay outside the United States, please call 617-801-6888 and use passcode 38751918.

The conference call will also be available via live webcast in the Investor Relations section of the Company's website at www.copt.com. A replay of the conference call will be immediately available via webcast in the Investor Relations section of the Company's website.

Definitions

Please refer to our Form 8-K or our website (www.copt.com) for definitions of certain terms used in this press release. Reconciliations of non-GAAP measures to the most directly comparable GAAP measures are included in the attached tables.

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 December 31, 2009, the Company owned 269 office and data properties totaling 20.2million rentable square feet, which includes 20 properties totaling 1.1 million 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. COPT is an S&P MidCap 400 company and more information 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 1A of the Company's Annual Report on Form 10-K for the year ended December 31, 2008.