SECOND AMENDMENT TO SECOND AMENDED AND RESTATED LIMITED PARTNERSHIP AGREEMENT OF CORPORATE OFFICE PROPERTIES, L.P. THIS SECOND AMENDMENT (the "Amendment") to the Second Amended and Restated Limited Partnership Agreement of Corporate Office Properties, L.P., a Delaware limited partnership (the "Partnership") is made and entered into as of December 21, 1999, by and among the undersigned parties. RECITALS A. The Partnership is a limited partnership organized under the Delaware Revised Uniform Limited Partnership Act and governed by that certain Seconded Amended and Restated Limited Partnership Agreement dated as of December 7, 1999, as amended by that certain First Amendment to Second Amended and Restated Limited Partnership Agreement dated December 21, 1999 (as amended, the "Partnership Agreement"). B. The sole general partner of the Partnership is Corporate Office Properties Trust, a real estate investment trust formed under the laws of the State of Maryland (the "General Partner"). C. COPT Acquisitions, Inc., a Delaware corporation and subsidiary of the Partnership, has entered into a certain Contribution Agreement (the "Contribution Agreement") dated as of December 3, 1999 with United Properties Group, Incorporated, a New York Corporation ("UPG"), which Contribution Agreement has been assigned to the Partnership in accordance with its terms. D. As required under Sections 2.2 and 3.1 of the Contribution Agreement, UPG intends to transfer certain membership interests in certain limited liability companies (the "Contributed Interests") to the Partnership in exchange for partnership interests in the Partnership having designations, rights and preferences as set forth in Sections 3 and 4 of the Contribution Agreement (the "Series C Preferred Units"). E. The parties desire to amend the Partnership Agreement to provide for the contribution of the Contributed Interests by UPG to the Partnership in exchange for the Series C Preferred Units in accordance with Section 3.1 of the Contribution Agreement. Unless otherwise defined herein, all capitalized terms used in this Amendment shall have the same meanings as set forth in the Partnership Agreement. NOW THEREFORE, in consideration of the foregoing and of the mutual premises set forth herein, the parties hereto, intending to be legally bound hereby, hereby amend the Partnership Agreement as follows, effective as of the date set forth above. 1. The foregoing recitals to this Amendment are hereby incorporated in and made a part of this Amendment. 2. (a) Upon closing of the Contribution Agreement, UPG shall contribute the Contributed Interests to the Partnership. (b) Upon the contribution of the Contributed Interests to the Partnership by UPG, and in accordance with Section 3.1 of the Contribution Agreement, the Partnership shall issue to UPG 974,662 Series C Preferred Units, which Preferred Units shall constitute Senior Preferred Units. (c) For purposes of the Partnership Agreement, including the maintenance of Capital Accounts, UPG shall be treated as making a Capital Contribution of $24,366,546.16, equal to the net asset value of the Contributed Interests. (d) The General Partner shall amend Exhibit 1 to the Partnership Agreement by adding the Addendum to Exhibit 1 in the form attached hereto to reflect the issuance of the Series C Preferred Units to UPG and the General Partner hereby confirms certain rights attendant thereto, including, without limitation, the rights to the Liquidation Preference and the Priority Return Percentage set forth therein, and the right to convert such Preferred Units into Partnership Units at the Conversion Factor set forth therein. The Conversion Factor for the Series C Preferred Units shall be entitled to anti-dilution protection to the same extent as that certain Warrant to Purchase Common Units dated of even date herewith of the Partnership in favor of UPG, granting UPG the right to purchase Partnership Units on the terms stated therein. 3. This Amendment shall take effect upon the closing of the transactions contemplated by the Contribution Agreement, including without limitation the contribution of the Contributed Interests to the Partnership by UPG, and in the event such closing does not occur, this Amendment shall be of no force or effect. (REMAINDER OF PAGE INTENTIONALLY LEFT BLANK) 2 In witness whereof, the parties hereto have caused their duly authorized representatives to execute this Amendment as of the day and year first above written. UNITED PROPERTIES GROUP, INCORPORATED, a New York corporation By: /s/ JOSEPH S. THOMPSON -------------------------------- Name: Joseph S. Thompson Its: Vice President CORPORATE OFFICE PROPERTIES TRUST, a Maryland Real Estate Investment Trust By: /s/ ROGER A. WAESCHE, JR. --------------------------------- Name: Roger A. Waesche, Jr. Its: Senior Vice President 3 Exhibit 1 SCHEDULE OF PARTNERS