Exhibit 4.8


                          REGISTRATION RIGHTS AGREEMENT

                          DATED AS OF JANUARY 25, 2001

                                       of

                        CORPORATE OFFICE PROPERTIES TRUST

                               for the benefit of

                              BARONY TRUST LIMITED





                          REGISTRATION RIGHTS AGREEMENT

      THIS REGISTRATION RIGHTS AGREEMENT (this "Agreement") is made and entered
into as of January 25, 2001 by Corporate Office Properties Trust, a Maryland
real estate investment trust (the "Company"), for the benefit of Barony Trust
Limited, an Isle of Man trust ("Barony").

      WHEREAS, on January 12, 2001, Barony became the owner of a certain
convertible promissory note issued by the Company (the "Note"), which Note is
convertible into Series D Cumulative Convertible Redeemable Preferred Shares of
Beneficial Interest, par value $0.01 per share (the "Series D Preferred Shares")
which, in turn, are convertible into Common Shares (as defined below);

      WHEREAS, contemporaneously with the execution of this Agreement, the Note
is being converted into Series D Preferred Shares, and the Company is issuing to
Barony the Series D Preferred Shares;

      WHEREAS, in connection with the foregoing, the Company is granting certain
registration rights to Barony consistent with the terms of Exhibit A to the
Note.

      NOW, THEREFORE, the Company for the benefit of Barony agrees as follows:

      SECTION 1.  DEFINITIONS.

      As used in this Agreement, the following capitalized defined terms shall
have the following meanings:

      Commission:  The Securities and Exchange Commission.

      Common Shares:  Common shares of beneficial interest, $0.01 par
value, of the Company.

      Exchange Act:  The Securities Exchange Act of 1934, as amended from
time to time.

      Holder or Holders:  The owners of the Registrable Securities.

      Indemnitee: A Holder of Registrable Securities covered by the registration
statement filed with the Commission as provided in this Agreement pursuant to
Section 2 hereof.

      Majority Holders:  At any time, Holders then holding a majority of
the Registrable Securities.

      NASD:  The National Association of Securities Dealers, Inc.

      Person:  Any individual, partnership, corporation, limited liability
company, trust or other legal entity.

      Prospectus: A prospectus included in the Shelf Registration Statement,
including any preliminary prospectus, and any such prospectus as amended or
supplemented by any prospectus supplement with respect to the terms of the
offering of any portion of the Registrable Securities covered


                                       2



by such Shelf Registration Statement, and by all other amendments and
supplements to such prospectus, including post-effective amendments, and in each
case including all material incorporated by reference therein.

      Registrable Securities: The Shares, excluding (i) Shares which shall have
been disposed of under the Shelf Registration Statement, (ii) Shares sold or
otherwise distributed pursuant to Rule 144 under the Securities Act and (iii)
Shares as to which registration under the Securities Act is not required to
permit the sale thereof to the public.

      Sale Period: The 45-day period immediately following the filing with the
Commission by the Company of an annual report of the Company on Form 10-K or a
quarterly report of the Company on Form 10-Q or such other period as the Company
may determine from time to time.

      Securities Act:  The Securities Act of 1933, as amended from time to
time.

      Shares:  The Common Shares issued to Holders of Series D Preferred
Shares upon conversion thereof.

      Shelf Registration:  A "shelf" registration of the Registrable
Securities under Rule 415 under the Securities Act.

      Shelf Registration Statement: A "shelf" registration statement of the
Company and any other entity required to be a registrant with respect to such
shelf registration statement pursuant to the requirements of the Securities Act
which covers all of the Registrable Securities then issued and outstanding or
which may thereafter be issued in redemption of any securities of the Company or
its affiliates on an appropriate form under Rule 415 under the Securities Act,
or any similar rule that may be adopted by the Commission, and all amendments
and supplements to such registration statement, including post-effective
amendments, in each case including the Prospectus contained therein, all
exhibits thereto and all materials incorporated by reference therein.

      SECTION 2.  SHELF REGISTRATION UNDER THE SECURITIES ACT.

      (a)   FILING OF SHELF REGISTRATION STATEMENT. By March 31, 2001, the
Company shall cause to be included in a Shelf Registration Statement all of the
Registrable Securities in accordance with the terms hereof and will use its
reasonable best efforts to cause such Shelf Registration Statement to be
declared effective by the Commission as soon as reasonably practicable. The
Company agrees to use its reasonable best efforts to keep such Shelf
Registration Statement continuously effective under the Securities Act until
such time as the aggregate number of Registrable Securities then outstanding, on
a fully diluted basis, is less than 5% of the then outstanding Common Shares,
and further agrees to supplement or amend such Shelf Registration Statement, if
and as required by the rules, regulations or instructions applicable to the
registration form used by the Company for such Shelf Registration Statement or
by the Securities Act or by any other rules and regulations thereunder for a
Shelf Registration. Each Holder who sells Shares as part of any such Shelf
Registration Statement shall be deemed to have agreed to all of the terms and
conditions of this Agreement and to have agreed to perform any an all
obligations of a Holder hereunder.

      (b)   SHELF REGISTRATION STATEMENT INFORMATION. Each Holder shall provide
the information reasonably requested by the Company in connection with the
preparation of the Shelf Registration Statement as promptly as practicable after
request by the Company, but in no event later than 20 days


                                       3



thereafter, and if such Holder shall not provide such information, shall not be
entitled to have its Registrable Securities included in such Shelf Registration
Statement after such 20 day period until such information is provided.

      SECTION 3.  SHELF REGISTRATION PROCEDURES.

      In connection with the obligations of the Company with respect to the
Shelf Registration Statement pursuant to Section 2 hereof, the Company shall:

      (a)   prepare and file with the SEC, within the time period set forth in
Section 2(a) hereof, an amendment to its current Shelf Registration Statement,
which Shelf Registration Statement (i) shall be available for the sale of the
Registrable Securities covered thereby in accordance with the intended method or
methods of distribution by the Holders thereof as set forth in the Prospectus
and (ii) shall comply as to form in all material respects with the requirements
of the applicable form and include all financial statements required by the
Commission to be filed therewith.

      (b)   subject to the last three sentences of this Section 3(b) and to
Section 3(i) hereof, (i) prepare and file with the Commission such amendments
and post-effective amendments to such Shelf Registration Statement as may be
necessary to keep such Shelf Registration Statement effective for the applicable
period set forth in Section 2; (ii) cause the Prospectus to be supplemented by
any required prospectus supplement, and as so supplemented to be filed pursuant
to Rule 424 or any similar rule that may be adopted under the Securities Act;
(iii) respond promptly to any comments received from the Commission with respect
to such Shelf Registration Statement, or any amendment, post-effective amendment
or supplement relating thereto; and (iv) comply with the provisions of the
Securities Act with respect to the disposition of all securities covered by such
Shelf Registration Statement during the applicable period in accordance with the
intended method or methods of distribution by the selling Holders thereof.
Notwithstanding anything to the contrary contained herein, the Company shall not
be required to take any of the actions described in clauses (i), (ii) or (iii)
above with respect to a particular Holder of Registrable Securities unless and
until the Company has received a written notice (a "Registration Notice") from
such Holder that it intends to make offers or sales under such Shelf
Registration Statement as specified in such Registration Notice; provided,
however, that the Company shall have 7 business days to prepare and file any
such amendment or supplement after receipt of a Registration Notice. Once a
Holder has delivered such a Registration Notice to the Company, such Holder
shall promptly provide to the Company such information as the Company reasonably
requests in order to identify such Holder and the method of distribution in a
post-effective amendment to such Shelf Registration Statement or a supplement to
a Prospectus. Offers or sales under such Shelf Registration Statement may be
made only during a Sale Period. Such Holder also shall notify the Company in
writing upon completion of such offer or sale or at such time as such Holder no
longer intends to make offers or sales under such Shelf Registration Statement.

      (c)   furnish to each Holder of Registrable Securities that has delivered
a Registration Notice to the Company, without charge, as many copies of each
applicable Prospectus, including each preliminary Prospectus, and any amendment
or supplement thereto and such other documents as such Holder may reasonably
request, in order to facilitate the public sale or other disposition of the
Registrable Securities; the Company consents to the use of such Prospectus,
including each preliminary Prospectus, by each such Holder of Registrable
Securities in connection with the offering and sale of the Registrable
Securities covered by such Prospectus or the preliminary Prospectus.


                                       4



      (d)   use its reasonable best efforts to register or qualify the
Registrable Securities covered thereby by the time such amendment to the Shelf
Registration Statement is declared effective by the Commission under all
applicable state securities or "blue sky" laws of such jurisdictions as any
Holder of Registrable Securities covered by such Shelf Registration Statement
shall reasonably request in writing, keep each such registration or
qualification effective during the period such Shelf Registration Statement is
required to be kept effective or during the period offers or sales are being
made by a Holder that has delivered a Registration Notice to the Company,
whichever is shorter, and do any and all other acts and things which may be
reasonably necessary or advisable to enable such Holder to consummate the
disposition in each such jurisdiction of such Registrable Securities then owned
by such Holder; provided, however, that the Company shall not be required (i) to
qualify generally to do business in any jurisdiction or to register as a broker
or dealer in such jurisdiction where it would not be required so to qualify or
register but for this Section 3(d), (ii) to subject itself to taxation in any
such jurisdiction or (iii) to submit to the general service of process in any
such jurisdiction.

      (e)   notify each Holder when such amendment to the Shelf Registration
Statement has become effective and notify each Holder of Registrable Securities
that has delivered a Registration Notice to the Company promptly and, if
requested by such Holder, confirm such advice in writing (i) when any
post-effective amendments and supplements to such Shelf Registration Statement
become effective, (ii) of the issuance by the Commission or any state securities
authority of any stop order suspending the effectiveness of such Shelf
Registration Statement or the initiation of any proceedings for that purpose,
(iii) if the Company receives any notification with respect to the suspension of
the qualification of the Registrable Securities for sale in any jurisdiction or
the initiation of any proceeding for such purpose and (iv) of the happening of
any event during the period such Shelf Registration Statement is effective as a
result of which such Shelf Registration Statement or a related Prospectus
contains any untrue statement of a material fact or omits to state any material
fact required to be stated therein or necessary to make the statements therein
(in the case of the Prospectus, in light of the circumstances under which they
were made) not misleading.

      (f)   make every reasonable effort to obtain the withdrawal of any order
suspending the effectiveness of such Shelf Registration Statement at the
earliest possible moment.

      (g)   furnish to each Holder of Registrable Securities covered thereby
that has delivered a Registration Notice to the Company, without charge, at
least one conformed copy of such Shelf Registration Statement and any
post-effective amendment thereto (without documents incorporated therein by
reference or exhibits thereto, unless requested).

      (h)   cooperate with the selling Holders of Registrable Securities covered
thereby to facilitate the timely preparation and delivery of certificates
representing Registrable Securities to be sold and not bearing any Securities
Act legend; and enable certificates for such Registrable Securities to be issued
for such numbers of shares and registered in such names as the selling Holders
may reasonably request at least two business days prior to any sale of
Registrable Securities.

      (i)   subject to the last three sentences of Section 3(b) hereof, upon the
occurrence of any event contemplated by Section 3(e)(iv) hereof, use its
reasonable best efforts promptly to prepare and file a supplement or prepare,
file and obtain effectiveness of a post-effective amendment to such Shelf
Registration Statement or a related Prospectus or any document incorporated
therein by reference or file any other required document so that, as thereafter
delivered to the purchasers of the Registrable Securities, such Prospectus will
not contain any untrue statement of a material fact or omit to state a


                                       5



material fact required to be stated therein or necessary to make the statements
therein, in the light of the circumstances under which they were made, not
misleading.

      (j)   make available for inspection by representatives of the Holders of
the Registrable Securities and any counsel or accountant retained by such
Holders, all financial and other records, pertinent corporate documents and
properties of the Company, and cause the respective officers, directors and
employees of the Company to supply all information reasonably requested by any
such representative, counsel or accountant in connection with such Shelf
Registration Statement; provided, however, that such records, documents or
information which the Company determines in good faith to be confidential, and
notifies such representatives, counsel or accountants in writing that such
records, documents or information are confidential, shall not be disclosed by
the representatives, counsel or accountants unless (i) the disclosure of such
records, documents or information is necessary to avoid or correct a material
misstatement or omission in such Shelf Registration Statement, (ii) the release
of such records, documents or information is ordered pursuant to a subpoena or
other order from a court of competent jurisdiction or (iii) such records,
documents or information have been generally made available to the public
otherwise than in violation of this Agreement.

      (k)   a reasonable time prior to the filing of any Prospectus, any
amendment to such Shelf Registration Statement or amendment or supplement to a
Prospectus, provide copies of such document (not including any documents
incorporated by reference therein unless requested) to the Holders of
Registrable Securities that have provided a Registration Notice to the Company.

      (l)   use its reasonable best efforts to cause all Registrable Securities
to be listed on any securities exchange on which similar securities issued by
the Company are then listed.

      (m)   continue to maintain a CUSIP number for all Registrable Securities.

      (n)   otherwise use its reasonable best efforts to comply with all
applicable rules and regulations of the Commission and make available to its
security holders, as soon as reasonably practicable, an earnings statement
covering at least 12 months which shall satisfy the provisions of Section 11(a)
of the Securities Act and Rule 158 thereunder.

      (o)   use its reasonable best efforts to cause the Registrable Securities
covered by such Shelf Registration Statement to be registered with or approved
by such other governmental agencies or authorities as may be necessary by virtue
of the business and operations of the Company to enable Holders that have
delivered Registration Notices to the Company to consummate the disposition of
such Registrable Securities.

      The Company may require each Holder of Registrable Securities to furnish
to the Company in writing such information regarding the proposed distribution
by such Holder of such Registrable Securities as the Company may from time to
time reasonably request in writing.

      In connection with and as a condition to the Company's obligations with
respect to any Shelf Registration Statement pursuant to Section 2 hereof and
this Section 3, each Holder agrees with the Company that:

            (i)   it will not offer or sell its Registrable Securities under a
      Shelf Registration Statement until (A) it has provided a Registration
      Notice pursuant to Section 3(b) hereof and


                                       6



      (B) it has received copies of the supplemented or amended Prospectus
      contemplated by Section 3(b) hereof and receives notice that any
      post-effective amendment has become effective;

            (ii)  upon receipt of any notice from the Company of the happening
      of any event of the kind described in Section 3(e)(iv) hereof, such Holder
      will forthwith discontinue disposition of Registrable Securities pursuant
      to such Shelf Registration Statement until such Holder receives copies of
      the supplemented or amended Prospectus contemplated by Section 3(i) hereof
      and receives notice that any post-effective amendment has become
      effective, and, if so directed by the Company, such Holder will deliver to
      the Company (at the expense of the Company) all copies in its possession,
      other than permanent file copies then in such Holder's possession, of the
      Prospectus covering such Registrable Securities current at the time of
      receipt of such notice;

            (iii) all offers and sales under such Shelf Registration Statement
      shall be completed within forty-five (45) days after the first date on
      which offers or sales can be made pursuant to clause (i) above, and upon
      expiration of such forty-five (45) day period the Holder will not offer or
      sell its Registrable Securities under the Shelf Registration Statement
      until it has again complied with the provisions of clauses (i)(A) and (B)
      above, except that if the applicable Registration Notice was delivered to
      the Company at a time which was not part of a Sale Period, such forty-five
      (45) day period shall be the next succeeding Sale Period;

            (iv)  if the Company determines in its good faith judgment, after
      consultation with counsel, that an amendment of a Shelf Registration
      Statement under Section 2 hereof or the use of any Prospectus would
      require the disclosure of important information which the Company has a
      bona fide business purpose for preserving as confidential or the
      disclosure of which would impede the Company's ability to consummate a
      significant transaction, upon written notice of such determination by the
      Company, the rights of the Holders to offer, sell or distribute any
      Registrable Securities pursuant to a Shelf Registration Statement or
      Prospectus or to require the Company to take action with respect to the
      registration or sale of any Registrable Securities pursuant to a Shelf
      Registration Statement (including any action contemplated by this Section
      3) will be suspended until the date upon which the Company notifies the
      Holders in writing that suspension of such rights for the grounds set
      forth in this paragraph is no longer necessary; provided, however, that
      the Company may not suspend such rights for an aggregate period of more
      than 90 days in any 12-month period; and

            (v)   in the case of the registration of any underwritten equity
      offering proposed by the Company (other than any registration by the
      Company on Form S-8, or a successor or substantially similar form, of (i)
      an employee stock option, stock purchase or compensation plan or of
      securities issued or issuable pursuant to any such plan or (ii) a dividend
      reinvestment plan), such Holder will agree, if requested in writing by the
      managing underwriter or underwriters administering such offering, not to
      effect any offer, sale or distribution of any Registrable Securities (or
      any option or right to acquire Registrable Securities) (each, a
      "Transfer") during the period commencing on the 10th day prior to the
      expected effective date (which date shall be stated in such notice) of the
      registration statement covering such underwritten primary equity offering
      or, if such offering shall be a "take-down" from an effective Shelf
      Registration Statement, the 10th day prior to the expected commencement
      date (which date shall be stated in such notice) of such offering, and
      ending on the date specified by such managing underwriter in such written
      request to such Holder; provided, however, that no Holder shall be
      required to agree not to Transfer its Registrable Securities for a period
      of time which is longer than the greater of 90 days or the period of time


                                       7



      for which any senior executive of the Company is required so to agree in
      connection with such offering.

      SECTION 4.  SELECTION OF UNDERWRITERS. If any offering pursuant to the
Shelf Registration Statement is to be an underwritten offering, the Company will
select a managing underwriter or underwriters to administer the offering.

      SECTION 5. REGISTRATION EXPENSES. The Company shall pay the following
registration expenses: (i) all Commission, stock exchange or NASD registration
and filing fees, (ii) all fees and expenses of compliance with securities or
blue sky laws (including reasonable fees and disbursements of counsel in
connection with the blue sky qualifications of the Registrable Securities),
(iii) printing expenses, (iv) internal expenses (including without limitation,
all salaries and expenses of its officers and employees performing legal or
accounting duties), (v) the fees and expenses incurred in connection with the
listing of the Registrable Securities on any national securities exchange or
interdealer quotation system, (vi) the reasonable fees and disbursements of
counsel for the Company and customary fees and expenses for independent
certified public accountants retained by the Company (including the expenses of
any comfort letters or costs associated with the delivery by independent
certified public accountants of a comfort letter or comfort letters), (vii) the
fees and expenses of any registrar and transfer agent for the Common Shares,
(viii) the underwriting fees, discounts and commissions applicable to any Common
Shares sold for the account of the Company and (ix) all expenses of any Person
in preparing or assisting in preparing, word processing, printing and
distributing any registration statement, prospectus, certificates and other
documents relating to the performance of and compliance with this Agreement.
Except as otherwise provided in clause (viii) of this Section 5, the Company
shall have no obligation to pay any underwriting fees, discounts or commissions
attributable to the sale of Registrable Securities.

      SECTION 6.  INDEMNIFICATION; CONTRIBUTION.

      (a)   The Company agrees to indemnify and hold harmless each Indemnitee
from and against any and all losses, claims, damages, liabilities and expenses
(including reasonable costs of investigation) arising out of or based upon any
untrue statement or alleged untrue statement of a material fact contained in any
prepricing prospectus, registration statement or prospectus or in any amendment
or supplement thereto, or arising out of or based upon any omission or alleged
omission to state therein a material fact required to be stated therein or
necessary to make the statements therein not misleading, except insofar as such
losses, claims, damages, liabilities or expenses arise out of or are based upon
any untrue statement or omission or alleged untrue statement or omission which
has been made therein or omitted therefrom in reliance upon and in conformity
with the information relating to a participating Holder furnished in writing to
the Company by or on behalf of a participating Holder expressly for use in
connection therewith. The foregoing indemnity agreement shall be in addition to
any liability which the Company may otherwise have.

      (b)   If any action, suit or proceeding shall be brought against an
Indemnitee in respect of which indemnity may be sought against the Company, such
Indemnitee shall promptly notify the Company, and the Company shall assume the
defense thereof, including the employment of counsel and payment of all fees and
expenses. The Indemnitee shall have the right to employ separate counsel in any
such action, suit or proceeding and to participate in the defense thereof, but
the fees and expenses of such counsel shall be at the expense of such Indemnitee
unless (x) the Company has agreed in writing to pay such fees and expenses, (y)
the Company has failed to assume the defense and employ counsel, or (z) the
named parties to any such action, suit or proceeding (including any impleaded


                                       8



parties) include both such Indemnitee and the Company, and such Indemnitee shall
have been advised by its counsel that representation of such Indemnitee and the
Company by the same counsel would be inappropriate under applicable standards of
professional conduct (whether or not such representation by the same counsel has
been proposed) due to actual or potential differing interests between them (in
which case the Company shall not have the right to assume the defense of such
action, suit or proceeding on behalf of such Indemnitee). It is understood,
however, that the Company shall, in connection with any one such action, suit or
proceeding or separate but substantially similar or related actions, suits or
proceedings in the same jurisdiction arising out of the same general allegations
or circumstances, be liable for the reasonable fees and expenses of only one
separate firm of attorneys (in addition to any local counsel) at any time for
all such Indemnitees not having actual or potential differing interests among
themselves, and that all such fees and expenses shall be reimbursed as they are
incurred. The Company shall not be liable for any settlement of any such action,
suit or proceeding effected without its written consent, but if settled with
such written consent, or if there be a final judgment for the plaintiff in any
such action, suit or proceeding, the Company agrees to indemnify and hold
harmless such Indemnitee, to the extent provided in the preceding paragraph,
from and against any loss, claim, damage, liability or expense by reason of such
settlement or judgment.

      (c)   Each of the participating Holders, severally and not jointly, agree
to indemnify and hold harmless the Company, its directors, its officers who sign
the registration statement, and any person who controls the Company within the
meaning of Section 15 of the Securities Act or Section 20 of the Exchange Act,
to the same extent as the foregoing indemnity from the Company to an Indemnitee,
but only with respect to information relating to such Holder furnished in
writing by or on behalf of such Holder expressly for use in the registration
statement, prospectus or any prepricing prospectus, or any amendment or
supplement thereto. If any action, suit or proceeding shall be brought against
the Company, any of its directors, any such officer, or any such controlling
person based on the registration statement, prospectus or any prepricing
prospectus, or any amendment or supplement thereto, and in respect of which
indemnity may be sought against any Holder pursuant to this Section 6(c), such
Holder shall have the rights and duties given to the Company by Section 6(b)
hereof (except that if the Company shall have assumed the defense thereof such
Holder shall not be required to do so, but may employ separate counsel therein
and participate in the defense thereof, but the fees and expenses of such
counsel shall be at the Holder's expense), and the Company, its directors, any
such officer, and any such controlling person shall have the rights and duties
given to an Indemnitee by Section 6(b) hereof. The foregoing indemnity agreement
shall be in addition to any liability which the participating Holders may
otherwise have.

      (d)   If the indemnification provided for in this Section 6 is unavailable
to an indemnified party under paragraphs (a) or (c) hereof in respect of any
losses, claims, damages, liabilities or expenses referred to therein, then an
indemnifying party, in lieu of indemnifying such indemnified party, shall
contribute to the amount paid or payable by such indemnified party as a result
of such losses, claims, damages, liabilities or expenses in such proportion as
is appropriate to reflect the relative fault of the Company and of the
participating Holders in connection with the statements or omissions that
resulted in such losses, claims, damages, liabilities or expenses. The relative
fault of the Company on the one hand and a participating Holder on the other
hand shall be determined by reference to, among other things, whether the untrue
or alleged untrue statement of a material fact or the omission or alleged
omission to state a material fact relates to information supplied by the Company
on the one hand or by such participating Holder on the other hand and the
parties' relative intent, knowledge, access or information and opportunity to
correct or prevent such statement or omission.


                                       9



      (e)   The Company and the participating Holders agree that it would not be
just and equitable if contribution pursuant to this Section 6 were determined by
a pro rata allocation or by any other method of allocation that does not take
account of the equitable considerations referred to in Section 6(d) hereof. The
amount paid or payable by an indemnified party as a result of the losses,
claims, damages, liabilities and expenses referred to in Section 6(d) hereof
shall be deemed to include, subject to the limitations set forth above, any
legal or other expenses reasonably incurred by such indemnified party in
connection with investigating any claim or defending any such action, suit or
proceeding. Notwithstanding the provisions of this Section 6, no participating
Holder shall be required to contribute any amount in excess of the amount by
which the proceeds to such participating Holder exceeds the amount of any
damages which such participating Holder has otherwise been required to pay by
reason of such untrue or alleged untrue statement or omission or alleged
omission. No person guilty of fraudulent misrepresentation (within the meaning
of Section 11(f) of the Securities Act) shall be entitled to contribution from
any person who was not guilty of such fraudulent misrepresentation.

      (f)   No indemnifying party shall, without the prior written consent of
the indemnified party, effect any settlement of any pending or threatened
action, suit or proceeding in respect of which any indemnified party is or could
have been a party and indemnity could have been sought hereunder by such
indemnified party, unless such settlement includes an unconditional release of
such indemnified party from all liability on claims that are the subject matter
of such action, suit or proceeding.

      (g)   Any losses, claims, damages, liabilities or expenses for which an
indemnified party is entitled to indemnification or contribution under this
Section 6 shall be paid by the indemnifying party to the indemnified party as
such losses, claims, damages, liabilities or expenses are incurred. The
indemnity and contribution agreements contained in this Section 6 shall remain
operative and in full force and effect, regardless of (i) any investigation made
by or on behalf of an Indemnitee, the Company, its directors or officers, or any
person controlling the Company, and (ii) any termination of this Agreement.

      SECTION 7.  PARTICIPATION IN UNDERWRITTEN REGISTRATIONS. A Holder may not
participate in any underwritten offering unless such Holder (i) agrees to sell
its Registrable Securities on the basis provided in any underwriting
arrangements which are approved by the Company in its reasonable discretion and
(ii) completes and executes all questionnaires, powers of attorney, indemnities,
underwriting agreements and other documents (including lock-up agreements)
reasonably required under the terms of such underwriting arrangements which are
not inconsistent with the terms of this Agreement.

      SECTION 8.  OTHER REGISTRATION RIGHTS. The Company is party to the Amended
and Restated Registration Rights Agreement dated as of March 16, 1998 and the
Registration Rights Agreement dated September 28, 1998 between the Company and
certain shareholders of the Company (together, the "Prior Registration Rights
Agreements"). In the event of any conflict between the provisions of this
Agreement and the Prior Registration Rights Agreements which would adversely
affect the rights exercisable by shareholders of the Company pursuant to the
Prior Registration Rights Agreement, the Holders hereby waive the enforcement of
the provisions of this Agreement to the extent necessary to alleviate such
conflict.


                                       10



      SECTION 9. RULE 144 SALES.

      (a)   The Company covenants that it will file the reports required to be
filed by the Company under the Securities Act and the Exchange Act, so as to
enable any Holder to sell Registrable Securities pursuant to Rule 144 under the
Securities Act.

      (b)   In connection with any sale, transfer or other disposition by any
Holder of any Registrable Securities pursuant to Rule 144 under the Securities
Act, the Company shall cooperate with such Holder to facilitate the timely
preparation and delivery of certificates representing Registrable Securities to
be sold and not bearing any Securities Act legend, and enable certificates for
such Registrable Securities to be for such number of shares and registered in
such names as the selling Holders may reasonably request at least two business
days prior to any sale of Registrable Securities.

      SECTION 10. MISCELLANEOUS.

      (a)   AMENDMENTS AND WAIVERS. The provisions of this Agreement, including
the provisions of this sentence, may be amended, modified or supplemented, and
waivers or consents to departures from the provisions hereof may be given with
the written consent of the Company and Holders constituting Majority Holders.
Notice of any amendment, modification or supplement to this Agreement adopted in
accordance with this Section 10(a) shall be provided by the Company to each
Holder of Registrable Securities at least thirty (30) days prior to the
effective date of such amendment, modification or supplement.

      (b)   NOTICES. All notices and other communications provided for or
permitted hereunder shall be made in writing by hand delivery, registered
first-class mail, telex, telecopier or any courier guaranteeing overnight
delivery, (i) if to a Holder, at the most current address given by such Holder
to the Company by means of a notice given in accordance with the provisions of
this Section 10(b), which address initially is, with respect to each Holder, at
7 Athol Street, Douglas, Isle of Man IM1 1LD, British Isles, Attention: Managing
Director, or (ii) if to the Company, at 8815 Centre Park Drive, Suite 400,
Columbia, Maryland 21045, Attention: General Counsel.

      All such notices and communications shall be deemed to have been duly
given: at the time delivered by hand, if personally delivered; five business
days after being deposited in the mail, postage prepaid, if mailed; when
answered back, if telexed; when receipt is acknowledged, if telecopied; or at
the time delivered if delivered by an air courier guaranteeing overnight
delivery.

      (c)   SUCCESSORS AND ASSIGNS. This Agreement shall inure to the benefit of
and be binding upon the successors, assigns and transferees of each of the
Company and the Holders, including without limitation and without the need for
an express assignment, subsequent Holders. If any successor, assignee or
transferee of any Holder shall acquire Registrable Securities, in any manner,
whether by operation of law or otherwise, such Registrable Securities shall be
held subject to all of the terms of this Agreement, and by taking and holding
such Registrable Securities such Person shall be entitled to receive the
benefits hereof and shall be conclusively deemed to have agreed to be bound by
all of the terms and provisions hereof.

      (d)   HEADINGS. The headings in this Agreement are for the convenience of
reference only and shall not limit or otherwise affect the meaning hereof.


                                       11



      (e)   GOVERNING LAW.  THIS AGREEMENT SHALL BE GOVERNED BY AND
CONSTRUED IN ACCORDANCE WITH THE LAWS OF THE COMMONWEALTH OF MARYLAND
WITHOUT GIVING EFFECT TO THE CONFLICTS OF LAW PROVISIONS THEREOF.

      (f)   SPECIFIC PERFORMANCE. The Company and the Holders acknowledge that
there would be no adequate remedy at law if any party fails to perform any of
its obligations hereunder, and accordingly agree that the Company and each
Holder, in addition to any other remedy to which it may be entitled at law or in
equity, shall be entitled to compel specific performance of the obligations of
another under this Agreement in accordance with the terms and conditions of this
Agreement in any court of the United States or any State thereof having
jurisdiction.

      (g)   ENTIRE AGREEMENT. This Agreement is intended by the Company as a
final expression of its agreement and is intended to be a complete and exclusive
statement of the agreement and understanding of the Company in respect of the
subject matter contained herein. This Agreement supersedes all prior agreements
and understandings of the Company with respect to such subject matter.




                      [SIGNATURE APPEARS ON FOLLOWING PAGE]


                                       12



      IN WITNESS WHEREOF, the Company has executed this Agreement as of the date
first written above.

                              CORPORATE OFFICE PROPERTIES TRUST

                              By:    /s/ Roger A. Waeche Jr.
                                  ------------------------------------
                                  Name:  Roger A. Waeche Jr.
                                  Title: Senior Vice President and CFO