COPT Announces Extension of Exchange Offer Deadline for 3.600% Senior Notes Due 2023

Corporate Office Properties Trust (“COPT”)

announces that its operating partnership, Corporate Office Properties, L.P. (the “Operating Partnership” and, together with COPT, the “Company”), has extended the expiration of its exchange offer from 5:00 p.m., New York City Time, on August 21, 2013 to 5:00 p.m., New York City Time, on August 28, 2013. Pursuant to the exchange offer, the Company has offered to exchange $350,000,000 in aggregate principal amount of its 3.600% Senior Notes due 2023 (the “Private Notes”), which were issued in May 2013 in a private placement pursuant to exemptions from registration under the Securities Act of 1933, as amended (the “Securities Act”), for an equal amount of newly issued 3.600% Senior Notes due 2023 (the “Exchange Notes”) which have been registered under the Securities Act. The Exchange Notes will have substantially the same terms as the Private Notes, except that the Exchange Notes will be registered under the Securities Act. As of 5:00 p.m., New York City time, on August 14, 2013, $349,000,000 in aggregate principal amount of the Private Notes (or approximately 99.71% of the Private Notes) had been tendered pursuant to the exchange offer. The exchange offer has been extended in order to allow additional time for the holders of the remaining $1,000,000 aggregate principal amount of the Private Notes to participate in the exchange offer. Except for the extension of the expiration date of the exchange offer for the Private Notes, all other terms, conditions and provisions of the exchange offer remain effective as of the date hereof. The terms of the exchange offer and other information relating to the Company are set forth in the prospectus dated July 16, 2013. Copies of the prospectus and the related letter of transmittal may be obtained from U.S. Bank National Association (“U.S. Bank”), which is serving as the exchange agent in connection with the exchange offer. Questions concerning the delivery of appropriate documentation for the exchange offer should be directed to the U.S. Bank. U.S. Bank's address, telephone number and facsimile number are as follows: