PEPCO STOCK OPTION AGREEMENT

                  This STOCK OPTION  AGREEMENT,  dated as of September 22, 1995,
(the  "Agreement")  by  and  between  Baltimore  Gas  and  Electric  Company,  a
corporation  formed under the laws of the State of Maryland  ("BGE") and Potomac
Electric Power Company,  a corporation  formed under the laws of the District of
Columbia and the Commonwealth of Virginia ("PEPCO"),


                          W I T N E S S E T H   T H A T:


                  WHEREAS,  concurrently with the execution and delivery of this
Agreement,  PEPCO, BGE and RH Acquisition  Corp., a corporation formed under the
laws of the State of Maryland  ("Company"),  are entering  into an Agreement and
Plan of Merger, dated as of September 22, 1995, (the "Merger Agreement"),  which
provides,  inter alia, upon the terms and subject to the conditions thereof, for
the merger of PEPCO and BGE with and into Company (the "Merger");

                  WHEREAS,  in  connection  with  the  execution  of the  Merger
Agreement,  PEPCO and BGE are entering  into a certain  stock  option  agreement
dated as of the date hereof  whereby BGE grants to PEPCO an option with  respect
to  certain  shares  of BGE's  common  stock on the  terms  and  subject  to the
conditions set forth therein (the "BGE Stock Option Agreement"); and

                  WHEREAS, as a condition to BGE's willingness to enter into the
Merger  Agreement,  BGE has requested that PEPCO agree, and PEPCO has so agreed,
to grant to BGE an option  with  respect  to certain  shares of  PEPCO's  common
stock, on the terms and subject to the conditions set forth herein;

                  NOW,  THEREFORE,  to  induce  BGE to  enter  into  the  Merger
Agreement  and the BGE  Stock  Option  Agreement,  and in  consideration  of the
representations,  warranties,  covenants and agreements contained herein, in the
Merger  Agreement  and in the BGE Stock Option  Agreement,  the parties  hereto,
intending to be legally bound, hereby agree as follows:

                  1.       GRANT OF OPTION.

                  (a) PEPCO hereby grants BGE an irrevocable  option (the "PEPCO
Option") to purchase up to 23,579,900 shares,  subject to adjustment as provided
in Section 11 (the "PEPCO Shares"),  of common stock, par value $1.00 per share,
of PEPCO (the  "PEPCO  Common  Stock")  (being  19.9% of the number of shares of
PEPCO  Common Stock  outstanding  as of August 31, 1995) in the manner set forth
below, at a price (the "Exercise Price") per PEPCO Share of







$21.225  (which is equal to the Fair Market Value (as defined  below) of a PEPCO
Share as of the date hereof).

                  (b)  The Exercise Price shall be payable, at BGE's
option, as follows:

                           (i)  in cash, or

                           (ii) subject to PEPCO's having obtained the approvals
         of any  Governmental  Authority  required  for PEPCO to acquire the BGE
         Shares (as defined below) from BGE, in shares of common stock,  without
         par value, of BGE ("BGE Shares"),

in either case in accordance with Section 4 hereof.

                  (c)  Notwithstanding  the  foregoing,  in no event  shall  the
number of PEPCO Shares for which the PEPCO Option is exercisable exceed 19.9% of
the number of issued and outstanding shares of PEPCO Common Stock.

                  (d) As used herein, the "Fair Market Value" of any share shall
be the average of the daily  closing  sales price for such share on the New York
Stock  Exchange (the "NYSE") during the ten NYSE trading days prior to the fifth
NYSE trading day preceding the date such Fair Market Value is to be determined.

                  (e) Capitalized terms used herein but not defined herein shall
have the meanings set forth in the Merger Agreement.

                  2.  EXERCISE OF OPTION.

                  (a) The PEPCO  Option may be  exercised by BGE, in whole or in
part,  at any time or from  time to time  after  the  Merger  Agreement  becomes
terminable by BGE under circumstances which could entitle BGE to a payment under
Section  9.3(b) of the  Merger  Agreement,  regardless  of  whether  the  Merger
Agreement  is  actually  terminated  or  whether  there  occurs a closing of any
Business  Combination  involving  a Target  Party or a closing by which a Target
Party becomes a subsidiary (any such event by which the Merger Agreement becomes
so terminable by BGE being referred to herein as a "Trigger Event").

                  (b) (i) PEPCO  shall  notify  BGE  promptly  in writing of the
         occurrence of any Trigger Event, it being understood that the giving of
         such notice by PEPCO  shall not be a  condition  to the right of BGE to
         exercise the PEPCO Option.

                       (ii) In the  event  BGE  wishes  to  exercise  the  PEPCO
         Option,  BGE  shall  deliver  to PEPCO  written  notice  (an  "Exercise
         Notice")  specifying  the  total  number  of PEPCO  Shares it wishes to
         purchase.



                                      -2-





                           (iii) Upon the giving by BGE to PEPCO of the Exercise
         Notice and the tender of the applicable  aggregate Exercise Price, BGE,
         to the extent  permitted by law and PEPCO's  organizational  documents,
         and provided  that the  conditions  to PEPCO's  obligation to issue the
         PEPCO  Shares  to BGE  hereunder  set  forth  in  Section  3 have  been
         satisfied or waived,  shall be deemed to be the holder of record of the
         PEPCO Shares  issuable  upon such  exercise,  notwithstanding  that the
         stock transfer books of PEPCO shall then be closed or that certificates
         representing such PEPCO Shares shall not then be actually  delivered to
         BGE.

                           (iv) Each  closing of a purchase  of PEPCO  Shares (a
         "Closing")  shall occur at a place, on a date, and at a time designated
         by BGE in an Exercise Notice delivered at least two business days prior
         to the date of the Closing.

                  (c)  The PEPCO Option shall terminate upon the earliest
to occur of:

                       (i) the Effective Time of the Merger;

                       (ii) the termination of the Merger Agreement  pursuant to
         Section 9.1 thereof other than under  circumstances which could entitle
         BGE to a payment under Section 9.3(b) of the Merger Agreement; and

                       (iii) 180 days  following any  termination  of the Merger
         Agreement upon or during the  continuance of a Trigger Event (or if, at
         the  expiration  of such 180 day  period,  the PEPCO  Option  cannot be
         exercised by reason of any applicable judgment,  decree,  order, law or
         regulation,  ten business days after such  impediment to exercise shall
         have been removed or shall have become final and not subject to appeal,
         but in no event under this clause (iii) later than March 31, 1998).

                  (d) Notwithstanding the foregoing, the PEPCO Option may not be
exercised  if BGE is in  material  breach  of  any  of  its  representations  or
warranties,  or in  material  breach  of  any of its  covenants  or  agreements,
contained in this Agreement or in the Merger Agreement.

                  3.  CONDITIONS TO CLOSING.  The obligation of PEPCO to
issue the PEPCO Shares to BGE hereunder is subject to the
conditions that

                  (a) all waiting periods,  if any, under the HSR Act applicable
to the  issuance of the PEPCO Shares  hereunder  shall have expired or have been
terminated;

                  (b) the PEPCO  Shares,  and any BGE Shares which are issued in
payment of the Exercise Price,  shall have been approved for listing on the NYSE
upon official notice of issuance;


                                      -3-






                  (c) all consents,  approvals,  orders or authorizations of, or
registrations,  declarations  or  filings  with,  any  federal,  state  or local
administrative   agency  or  commission  or  other   federal,   state  or  local
Governmental  Authority, if any, required in connection with the issuance of the
PEPCO Shares  hereunder  shall have been  obtained or made,  including,  without
limitation,  the  approval  of the SEC under  Section  10 of the 1935  Act,  the
approval of the D.C.  Commission  of the  issuance of the PEPCO  Shares by PEPCO
and, if applicable,  the acquisition of PEPCO Shares by BGE, and the approval of
the Maryland  Commission of the  acquisition  of the PEPCO Shares by BGE and, if
applicable, the acquisition by PEPCO of the BGE Shares constituting the Exercise
Price hereunder; and

                  (d) no preliminary  or permanent  injunction or other order by
any court of competent  jurisdiction  prohibiting or otherwise  restraining such
issuance shall be in effect.

The condition  set forth in paragraph  (b) above may be waived by PEPCO,  in the
case of BGE  Shares,  and by BGE,  in the  case of  PEPCO  Shares,  in the  sole
discretion of the waiving party.

                  4.  CLOSING.  At any Closing,

                  (a)  PEPCO  shall  deliver  to BGE or its  designee  a  single
certificate  in  definitive  form   representing  the  number  of  PEPCO  Shares
designated by BGE in its Exercise  Notice,  such certificate to be registered in
the name of BGE and to bear the legend set forth in Section 12; and

                  (b)  BGE shall deliver to PEPCO the aggregate price for
the PEPCO Shares so designated and being purchased by

                           (i)  wire transfer of immediately available funds
         or certified check or bank check, or

                           (ii) subject to the condition in Section 1(b)(ii),  a
         certificate or certificates representing the number of BGE Shares being
         issued by BGE in consideration  thereof,  determined in accordance with
         Section 4(c).

                  (c) In the  event  that  BGE  issues  BGE  Shares  to PEPCO in
consideration  of PEPCO Shares pursuant to Section  4(b)(ii),  the number of BGE
Shares to be so issued shall be equal to the quotient obtained by dividing:

                           (i)  the product of (x) the number of PEPCO Shares
         with respect to which the PEPCO Option is being exercised
         and (y) the Exercise Price, by

                           (ii) the Fair  Market  Value of the BGE  Shares as of
         the  date  immediately  preceding  the  date  the  Exercise  Notice  is
         delivered to PEPCO.



                                      -4-





                  (d)  PEPCO  shall  pay all  expenses,  and any and all  United
States Federal,  state and local taxes, and other charges that may be payable in
connection with the preparation,  issue and delivery of stock certificates under
this Section 4.

                  5.  REPRESENTATIONS AND WARRANTIES OF PEPCO.  PEPCO
represents and warrants to BGE that

                  (a) Subject to any required  regulatory  approvals,  PEPCO has
the corporate  power and authority to enter into this Agreement and to carry out
its  obligations  hereunder,  subject in the case of the repurchase of the PEPCO
Shares  pursuant to Section 7(a) to applicable law and the provisions of PEPCO's
Articles of Incorporation, as amended (the "PEPCO Articles");

                  (b) this  Agreement  has been duly and  validly  executed  and
delivered by PEPCO, and, assuming the due authorization,  execution and delivery
hereof by BGE, constitutes a valid and binding obligation of PEPCO,  enforceable
against  PEPCO in  accordance  with  its  terms,  except  as may be  limited  by
applicable  bankruptcy,  insolvency,  fraudulent  conveyance,  reorganization or
other similar laws affecting the enforcement of creditors' rights generally, and
except  that  the  availability  of  equitable   remedies,   including  specific
performance,  may be subject to the  discretion  of any court  before  which any
proceeding therefor may be brought;

                  (c)  PEPCO  has  taken  all  necessary   corporate  action  to
authorize  and reserve for issuance and to permit it to issue,  upon exercise of
the PEPCO Option,  and at all times from the date hereof  through the expiration
of the PEPCO Option will have reserved, 23,579,900 authorized and unissued PEPCO
Shares,  such amount being  subject to adjustment as provided in Section 11, all
of which,  upon their issuance and delivery in accordance with the terms of this
Agreement, will be validly issued, fully paid and nonassessable;

                  (d) upon delivery of the PEPCO Shares to BGE upon the exercise
of the PEPCO  Option,  BGE will  acquire the PEPCO  Shares free and clear of all
claims,  liens,  charges,  encumbrances  and  security  interests  of any nature
whatsoever;

                  (e)  except as  described  in  Section  4.4(b)  of the  Merger
Agreement,  the execution and delivery of this Agreement by PEPCO does not, and,
subject to compliance with applicable law and the PEPCO Articles with respect to
the repurchase of the PEPCO Shares pursuant to Section 7(a), the consummation by
PEPCO of the transactions  contemplated hereby will not, violate, conflict with,
or result in a breach of any  provision  of, or  constitute  a default  (with or
without notice or a lapse of time, or both) under,  or result in the termination
of,  or  accelerate  the  performance  required  by,  or  result  in a right  of
termination,  cancellation,  or  acceleration of any obligation or the loss of a
material benefit under, or the creation of a lien, pledge,


                                      -5-





security interest or other encumbrance on assets (any such conflict,  violation,
default, right of termination,  cancellation or acceleration,  loss or creation,
hereinafter a "Violation") of PEPCO or any of its subsidiaries, pursuant to

                           (i) any provision of the PEPCO Articles or the
         Bylaws of PEPCO,

                           (ii) any  provisions  of any material  loan or credit
         agreement,  note,  mortgage,  indenture,  lease,  PEPCO benefit plan or
         other agreement, obligation, instrument, permit, concession, franchise,
         license  (any of the  foregoing  in  effect  on the date  hereof  being
         referred to as a "Material Contract"), or

                           (iii) any judgment, order, decree, statute, law,
         ordinance, rule or regulation applicable to PEPCO or its
         properties or assets,

which Violation, in the case of each of clauses (ii) and (iii), could reasonably
be  expected  to  have  a  PEPCO   Material   Adverse  Effect  (except  that  no
representation  or  warranty is given  concerning  any  Violation  of a Material
Contract  with respect to the  repurchase  of PEPCO  Shares  pursuant to Section
7(a));

                  (f)  except as  described  in  Section  4.4(c)  of the  Merger
Agreement or Section 3 hereof,  the execution and delivery of this  Agreement by
PEPCO does not, and the performance of this Agreement by PEPCO will not, require
any consent,  approval,  authorization  or permit or filing with or notification
to, any Governmental Authority;

                  (g) none of PEPCO,  any of its  affiliates or anyone acting on
its or their  behalf,  has issued,  sold or offered any security of PEPCO to any
person  under  circumstances  that would  cause the  issuance  and sale of PEPCO
Shares,  as contemplated by this  Agreement,  to be subject to the  registration
requirements  of the  Securities  Act as in  effect  on the  date  hereof,  and,
assuming the representations and warranties of BGE contained in Section 6(g) are
true and correct, the issuance,  sale and delivery of the PEPCO Shares hereunder
would be exempt from the  registration and prospectus  delivery  requirements of
the  Securities  Act,  as in effect on the date hereof (and PEPCO shall not take
any action which would cause the  issuance,  sale,  and delivery of PEPCO Shares
hereunder not to be exempt from such requirements); and

                  (h) any BGE Shares acquired pursuant to this Agreement will be
acquired for PEPCO's own account,  for investment purposes only, and will not be
acquired by PEPCO with a view to the public distribution thereof in violation of
any applicable provision of the Securities Act.

                  6.  REPRESENTATIONS  AND WARRANTIES OF BGE. BGE represents and
warrants to PEPCO that


                                      -6-






                  (a) BGE has the  corporate  power and  authority to enter into
this Agreement and to carry out its obligations hereunder;

                  (b) this  Agreement  has been duly and  validly  executed  and
delivered by BGE and,  assuming the due  authorization,  execution  and delivery
hereof,  constitutes a valid and binding obligation of BGE,  enforceable against
BGE in  accordance  with  their  respective  terms,  except as may be limited by
applicable  bankruptcy,  insolvency,   reorganization,  or  other  similar  laws
affecting the enforcement of creditors'  rights  generally,  and except that the
availability  of equitable  remedies,  including  specific  performance,  may be
subject  to the  discretion  of any court  before  which any  proceeding  may be
brought;

                  (c) prior to any  delivery of BGE Shares in  consideration  of
the purchase of PEPCO Shares pursuant hereto,  BGE will have taken all necessary
corporate  action to  authorize  for issuance and to permit it to issue such BGE
Shares,  all of which,  upon their issuance and delivery in accordance  with the
terms of this Agreement, will be validly issued, fully paid and nonassessable;

                  (d)  upon  any  delivery  of  such  BGE  Shares  to  PEPCO  in
consideration  of the  purchase  of PEPCO  Shares  pursuant  hereto,  PEPCO will
acquire  the  BGE  Shares  free  and  clear  of  all  claims,   liens,  charges,
encumbrances and security interests of an nature whatsoever;

                  (e)  except as  described  in  Section  5.4(b)  of the  Merger
Agreement, the execution and delivery of this Agreement by BGE does not, and the
consummation by BGE of the transactions  contemplated  hereby will not, violate,
conflict  with,  or result in the breach of any  provision  of, or  constitute a
default (with or without notice or a lapse of time, or both) under, or result in
any Violation by BGE or any of its subsidiaries, pursuant to

                      (i) any  provision  of the  Articles of  Incorporation  or
         Bylaws of BGE,

                      (ii) any provisions of any loan or credit agreement, note,
         mortgage,  indenture,  lease,  BGE  benefit  plan or  other  agreement,
         obligation, instrument, permit, concession, franchise, license, or

                      (iii)  any  judgment,   order,   decree,   statute,   law,
         ordinance,  rule or regulation  applicable to BGE or its  properties or
         assets,

which Violation,  in the case of each of clauses (ii) or (iii), would have a BGE
Material Adverse Effect;

                  (f)  except as  described  in  Section  5.4(c)  of the  Merger
Agreement or Section 3 hereof,  the execution and delivery of this  Agreement by
BGE does not, and the consummation by BGE of


                                      -7-





the transactions  contemplated  hereby will not, require any consent,  approvals
authorization  or permit of, or filing with or notification to, any Governmental
Authority; and

                  (g) any  PEPCO  Shares  acquired  upon  exercise  of the PEPCO
Option will be acquired for BGE's own account,  for investment purposes only and
will not be, and the PEPCO  Option is not being,  acquired by BGE with a view to
the public distribution thereof, in violation of any applicable provision of the
Securities Act.

                  7.  CERTAIN REPURCHASES.

                  (a) BGE "PUT".  At the request of BGE by written notice (x) at
any time during which the PEPCO Option is exercisable pursuant to Section 2 (the
"Repurchase  Period"),  PEPCO  (or  any  successor  entity  thereof)  shall,  if
permitted by applicable law, the PEPCO Articles and PEPCO's  Material  Contracts
(but  notwithstanding any insufficiency in the number of PEPCO Shares authorized
for issuance upon the exercise of the PEPCO Option),  repurchase from BGE all or
any  portion of the PEPCO  Option,  at the price set forth in  subparagraph  (i)
below,  or, (y) at any time  prior to March 31,  1997  (provided  that such date
shall be extended to March 31, 1998 under the circumstances where the date after
which either party may terminate the Merger Agreement pursuant to Section 9.1(b)
of the Merger  Agreement  has been  extended to March 31,  1998),  PEPCO (or any
successor  entity  thereof)  shall,  if permitted by  applicable  law, the PEPCO
Articles and PEPCO's Material Contracts,  repurchase from BGE all or any portion
of the PEPCO Shares purchased by BGE pursuant to the PEPCO Option,  at the price
set forth in subparagraph (ii) below:

                           (i) the difference  between the "Market/Offer  Price"
         (as defined  below) for shares of PEPCO Common Stock as of the date BGE
         gives  notice of its intent to exercise its rights under this Section 7
         and the  Exercise  Price,  multiplied  by the  number  of PEPCO  Shares
         purchasable  pursuant  to the PEPCO  Option (or  portion  thereof  with
         respect to which BGE is  exercising  its rights  under this Section 7),
         but only if the Market/Offer  Price is greater than the Exercise Price.
         For purposes of this subparagraph (i), "Market/Offer Price" shall mean,
         as of any date,  the  higher of (x) the price per share  offered  as of
         such date pursuant to any tender or exchange  offer or other offer with
         respect to a Business  Combination  involving PEPCO as the Target Party
         which was made prior to such date and not terminated or withdrawn as of
         such date and (y) the Fair  Market  Value of PEPCO  Common  Stock as of
         such date.

                           (ii) the  product of (x) the sum of (A) the  Exercise
         Price  paid by BGE per  PEPCO  Share  acquired  pursuant  to the  PEPCO
         Option,  and (B) the  difference  between the "Offer Price" (as defined
         below) and the Exercise Price, but


                                      -8-





         only if the Offer Price is greater than the Exercise Price, and (y) the
         number of PEPCO Shares so to be repurchased pursuant to this Section 7.
         For  purposes  of this  clause  (ii),  the "Offer  Price"  shall be the
         highest price per share offered  pursuant to a tender or exchange offer
         or other Business Combination offer involving PEPCO as the Target Party
         during the  Repurchase  Period prior to the delivery by BGE of a notice
         of repurchase.

                  (b)  REDELIVERY  OF BGE SHARES.  If BGE shall have  previously
elected to purchase PEPCO Shares pursuant to the exercise of the PEPCO Option by
the issuance and  delivery of BGE Shares,  then PEPCO shall,  if so requested by
BGE, in fulfillment of its obligation pursuant to Section 7(a)(y) (that is, with
respect to the Exercise  Price only and without  limitation to its obligation to
pay additional consideration under clause (B) of Section 7(a)(ii)(x)), redeliver
the  certificates  for such BGE  Shares  to BGE,  free and  clear of all  liens,
claims,  charges and  encumbrances of any kind or nature  whatsoever;  provided,
however,  that if at any time less than all of the PEPCO  Shares so purchased by
BGE  pursuant to the PEPCO  Option are to be  repurchased  by PEPCO  pursuant to
Section 7(a)(y),  then (i) PEPCO shall be obligated to redeliver to BGE the same
proportion of such BGE Shares as the number of PEPCO  Shares  that PEPCO is then
obligated to repurchase bears to the number of PEPCO Shares acquired by BGE upon
exercise of the PEPCO Option and (ii) BGE shall issue to PEPCO new  certificates
representing  those  BGE  Shares  which  are  not due to be  redelivered  to BGE
pursuant to this  Section 7(b) to the extent that excess BGE Shares are included
in the certificates redelivered to BGE by PEPCO.

                  (c) PAYMENT AND REDELIVERY OF PEPCO OPTIONS OR SHARES.  In the
event BGE  exercises  its rights under this  Section 7, PEPCO shall,  within ten
business  days  thereafter,  pay  the  required  amount  to BGE  in  immediately
available  funds  and BGE  shall  surrender  to PEPCO  the  PEPCO  Option or the
certificate  or  certificates  evidencing  the  PEPCO  Shares  purchased  by BGE
pursuant  hereto,  and BGE shall  warrant  that it owns the PEPCO Option or such
shares and that the PEPCO  Option or such  shares are then free and clear of all
liens,  claims,  damages,  charges  and  encumbrances  of  any  kind  or  nature
whatsoever.

                  (d) BGE "CALL".  If BGE has elected to purchase  PEPCO  Shares
pursuant to the exercise of the PEPCO Option by the issuance and delivery of BGE
Shares,  notwithstanding  that BGE may no longer  hold any such PEPCO  Shares or
that BGE elects not to exercise  its other  rights under this Section 7, BGE may
require, at any time or from time to time prior to March 31, 1997 (provided that
such date shall be extended to March 31, 1998 under the circumstances  where the
date after which either party may  terminate  the Merger  Agreement  pursuant to
Section  9.1(b) of the Merger  Agreement  has been  extended to March 31, 1998),
PEPCO to sell to BGE any such BGE  Shares  at the price  attributed  to such BGE
Shares pursuant to Section 4 plus interest at the rate


                                      -9-





of 8.75% per annum on such amount from the Closing Date relating to the exchange
of such BGE Shares  pursuant to Section 4 to the Closing Date under this Section
7(d) less any  dividends  on such BGE Shares paid during such period or declared
and payable to stockholders of record on a date during such period.

                  (e) REPURCHASE PRICE REDUCED AT BGE'S OPTION. In the event the
repurchase  price  specified in Section  7(a) would  subject the purchase of the
PEPCO Option or the PEPCO  Shares  purchased by BGE pursuant to the PEPCO Option
to a vote of the  shareholders  of PEPCO pursuant to applicable law or the PEPCO
Articles,  then BGE may,  at its  election,  reduce the  repurchase  price to an
amount  which would  permit such  repurchase  without the  necessity  for such a
shareholder vote.

                  8.  VOTING OF SHARES.  Following  the date hereof and prior to
the fifth  anniversary of the date hereof (the  "Expiration  Date"),  each party
shall vote any shares of capital stock of the other party acquired by such party
pursuant  to this  Agreement  ("Restricted  Shares"),  including  any BGE Shares
issued  pursuant to Section  1(b), or otherwise  beneficially  owned (within the
meaning of Rule 13d-3 promulgated under the Securities  Exchange Act of 1934, as
amended (the "Exchange  Act")), by such party on each matter submitted to a vote
of  shareholders  of such other  party for and  against  such matter in the same
proportion as the vote of all other  shareholders  of such other party are voted
(whether by proxy or otherwise) for and against such matter.

                  9.       RESTRICTIONS ON TRANSFER.

                  (a)  RESTRICTIONS ON TRANSFER.  Prior to the Expiration  Date,
neither party shall,  directly or indirectly,  by operation of law or otherwise,
sell, assign,  pledge, or otherwise dispose of or transfer any Restricted Shares
beneficially  owned by such party, other than (i) pursuant to Section 7, or (ii)
in accordance with Section 9(b) or Section 10.

                  (b) PERMITTED  SALES.  Following the termination of the Merger
Agreement, a party shall be permitted to sell any Restricted Shares beneficially
owned by it if such sale is made pursuant to a tender or exchange offer that has
been approved or recommended,  or otherwise  determined to be fair to and in the
best  interests of the  shareholders  of the other  party,  by a majority of the
members of the Board of  Directors  of such other party,  which  majority  shall
include a majority of directors who were directors prior to the  announcement of
such tender or exchange offer.

                  10.      REGISTRATION RIGHTS.

                  (a) Following the termination of the Merger Agreement,  either
party hereto that owns Restricted Shares (a "Designated  Holder") may by written
notice (the "Registration Notice") to the other party (the "Registrant") request
the Registrant to register


                                      -10-





under the Securities Act all or any part of the Restricted  Shares  beneficially
owned by such Designated  Holder (the  "Registrable  Securities")  pursuant to a
bona fide firm commitment  underwritten public offering, in which the Designated
Holder  and  the  underwriters  shall  effect  as  wide a  distribution  of such
Registrable  Securities  as is reasonably  practicable  and shall use their best
efforts to prevent any person  (including any Group (as used in Rule 13d-5 under
the Exchange  Act)) and its  affiliates  from  purchasing  through such offering
Restricted Shares  representing more than 1% of the outstanding shares of common
stock of the Registrant on a fully diluted basis (a "Permitted Offering").

                  (b)  The  Registration  Notice  shall  include  a  certificate
executed by the Designated Holder and its proposed managing  underwriter,  which
underwriter  shall  be an  investment  banking  firm  of  nationally  recognized
standing (the "Manager"), stating that

                           (i) they have a good faith intention to commence
         promptly a Permitted Offering, and

                           (ii) the Manager in good faith believes  that,  based
         on the then-prevailing  market conditions,  it will be able to sell the
         Registrable  Securities  at a per share  price equal to at least 80% of
         the then Fair Market Value of such shares.

                  (c)  The  Registrant  (and/or  any  person  designated  by the
Registrant)  shall  thereupon  have the option  exercisable  by  written  notice
delivered to the Designated Holder within ten business days after the receipt of
the Registration Notice, irrevocably to agree to purchase all or any part of the
Registrable  Securities  proposed to be so sold for cash at a price (the "Option
Price") equal to the product of (i) the number of  Registrable  Securities to be
so  purchased  by the  Registrant  and (ii) the then Fair  Market  Value of such
shares.

                  (d) Any purchase of  Registrable  Securities by the Registrant
(or its  designee)  under Section 10(c) shall take place at a closing to be held
at the principal  executive  offices of the  Registrant or at the offices of its
counsel at any reasonable date and time designated by the Registrant and/or such
designee in such  notice  within  twenty  business  days after  delivery of such
notice,  and any  payment  for the  shares to be so  purchased  shall be made by
delivery at the time of such closing in immediately available funds.

                  (e) If the  Registrant  does not elect to exercise  its option
pursuant to this Section 10 with respect to all Registrable Securities, it shall
use its best efforts to effect,  as promptly as  practicable,  the  registration
under the Securities Act of the unpurchased  Registrable  Securities proposed to
be so sold; provided, however, that


                                      -11-






                           (i) neither party shall be entitled to more than
         an aggregate of two effective registration statements
         hereunder, and

                           (ii) the Registrant  will not be required to file any
         such registration statement during any period of time (not to exceed 40
         days after  such  request in the case of clause (A) below or 90 days in
         the case of clauses (B) and (C) below) when

                  (A) the  Registrant is in  possession  of material  non-public
information which it reasonably believes would be detrimental to be disclosed at
such time and, in the  opinion of counsel to the  Registrant,  such  information
would have to be disclosed if a registration statement were filed at that time;

                  (B) the  Registrant is required  under the  Securities  Act to
include  audited  financial  statements  for any  period  in  such  registration
statement and such  financial  statements are not yet available for inclusion in
such registration statement; or

                  (C) the Registrant  determines,  in its  reasonable  judgment,
that such registration would interfere with any financing,  acquisition or other
material transaction involving the Registrant or any of its affiliates.

                    (f) The Registrant  shall use its reasonable best efforts to
cause any Registrable  Securities  registered  pursuant to this Section 10 to be
qualified for sale under the  securities or Blue Sky laws of such  jurisdictions
as the  Designated  Holder  may  reasonably  request  and  shall  continue  such
registration or qualification in effect in such jurisdiction; provided, however,
that the  Registrant  shall not be  required  to qualify to do  business  in, or
consent to general  service of process  in, any  jurisdiction  by reason of this
provision.

                  (g) The  registration  rights set forth in this Section 10 are
subject to the condition that the Designated Holder shall provide the Registrant
with such information with respect to such holder's Registrable Securities,  the
plans for the distribution  thereof,  and such other information with respect to
such holder as, in the  reasonable  judgment of counsel for the  Registrant,  is
necessary to enable the Registrant to include in such registration statement all
material  facts  required  to  be  disclosed  with  respect  to  a  registration
thereunder.

                  (h) A  registration  effected  under this  Section 10 shall be
effected at the  Registrant's  expense,  except for  underwriting  discounts and
commissions  and the fees and the expenses of counsel to the Designated  Holder,
and  the  Registrant  shall  provide  to  the  underwriters  such  documentation
(including  certificates,   opinions  of  counsel  and  "comfort"  letters  from
auditors) as is customary in connection with  underwritten  public  offerings as
such underwriters may reasonably require.


                                      -12-






                  (i)  In connection with any registration effected under
this Section 10, the parties agree

                       (i) to indemnify each other and the  underwriters  in the
         customary manner,

                       (ii) to enter into an underwriting  agreement in form and
         substance  customary for transactions of such type with the Manager and
         the other underwriters participating in such offering, and

                       (iii)  to  take  all  further   actions  which  shall  be
         reasonably necessary to effect such registration and sale (including if
         the   Manager   deems  it   necessary,   participating   in   road-show
         presentations).

                  (j) The  Registrant  shall  be  entitled  to  include  (at its
expense)  additional  shares  of its  common  stock in a  registration  effected
pursuant  to this  Section 10 only if and to the extent the  Manager  determines
that such inclusion will not adversely  affect the prospects for success of such
offering.

                  11.  ADJUSTMENT  UPON  CHANGES  IN   CAPITALIZATION.   Without
limitation to any  restriction  on PEPCO  contained in this  Agreement or in the
Merger Agreement,  in the event of any change in PEPCO Common Stock by reason of
stock dividends,  splitups, mergers (other than the Merger),  recapitalizations,
combinations,  exchange of shares or the like,  the type and number of shares or
securities  subject  to the  PEPCO  Option,  and the  purchase  price  per share
provided  in Section 1, shall be  adjusted  appropriately  to restore to BGE its
rights hereunder, including the right to purchase from PEPCO (or its successors)
shares of PEPCO Common Stock  representing 19.9% of the outstanding PEPCO Common
Stock  for  the  aggregate  Exercise  Price  calculated  as of the  date of this
Agreement as provided in Section 1.

                  12. RESTRICTIVE LEGENDS. Each certificate  representing shares
of PEPCO Common Stock issued to BGE hereunder, and BGE Shares, if any, delivered
to PEPCO at a Closing,  shall  include a legend in  substantially  the following
form:

         THE SECURITIES REPRESENTED BY THIS CERTIFICATE HAVE NOT BEEN REGISTERED
         UNDER THE SECURITIES ACT OF 1933, AS AMENDED,  OR ANY STATE  SECURITIES
         OR BLUE SKY LAWS, AND MAY BE REOFFERED OR SOLD ONLY IF SO REGISTERED OR
         IF AN EXEMPTION FROM SUCH  REGISTRATION  IS AVAILABLE.  SUCH SECURITIES
         ARE ALSO SUBJECT TO ADDITIONAL RESTRICTIONS ON TRANSFER AS SET FORTH IN
         THE PEPCO STOCK OPTION  AGREEMENT,  DATED AS OF  SEPTEMBER  22, 1995, A
         COPY OF WHICH MAY BE OBTAINED FROM THE ISSUER UPON REQUEST.



                                      -13-





It is understood and agreed that:

                           (i) the reference to the resale  restrictions  of the
         Securities  Act and  state  securities  or Blue Sky  laws in the  above
         legend  shall be  removed  by  delivery  of  substitute  certificate(s)
         without such reference if BGE or PEPCO,  as the case may be, shall have
         delivered  to the other  party a copy of a letter from the staff of the
         SEC, or an opinion of counsel,  in form and substance  satisfactory  to
         the other  party,  to the effect that such legend is not  required  for
         purposes of the Securities Act or such laws;

                           (ii)  the   reference  to  the   provisions  to  this
         Agreement  in  the  above  legend  shall  be  removed  by  delivery  of
         substitute  certificate(s)  without  such  reference if the shares have
         been sold or  transferred  in  compliance  with the  provisions of this
         Agreement and under  circumstances that do not require the retention of
         such reference; and

                           (iii) the legend  shall be removed in its entirety if
         the  conditions  in  the  preceding  clauses  (i)  and  (ii)  are  both
         satisfied.

In addition, such certificates shall bear any other legend as may be required by
law.  Certificates  representing  shares sold in a  registered  public  offering
pursuant  to  Section 10 shall not be  required  to bear the legend set forth in
this Section 12.

                  13.   BINDING   EFFECT;   NO   ASSIGNMENT;   NO  THIRD   PARTY
BENEFICIARIES. (a) This Agreement shall be binding upon and inure to the benefit
of the parties hereto and their respective successors and permitted assigns.

                  (b)  Except  as  expressly  provided  for in  this  Agreement,
neither this  Agreement nor the rights or obligations of either party hereto are
assignable, except by operation of law, or with the written consent of the other
party.

                  (c) Nothing  contained in this Agreement,  express or implied,
is intended to confer  upon any person  other than the parties  hereto and their
respective  permitted assigns any rights or remedies of any nature whatsoever by
reason of this Agreement.

                  (d) Any Restricted  Shares sold by a party in compliance  with
the provisions of Section 10 shall,  upon  consummation of such sale, be free of
the restrictions  imposed with respect to such shares by this Agreement,  unless
and until such party shall  repurchase or otherwise  become the beneficial owner
of such shares,  and any  transferee of such shares shall not be entitled to the
registration rights of such party.

                  14.  SPECIFIC  PERFORMANCE.  The  parties  hereto  agree  that
irreparable  harm would  occur in the event that any of the  provisions  of this
Agreement were not performed in accordance


                                      -14-





with their specified terms or were otherwise breached.  It is accordingly agreed
that the parties  hereto shall be entitled to an  injunction or  injunctions  to
prevent  breaches of this  Agreement and to enforce  specifically  the terms and
provisions  hereof  in any  court  of the  United  States  or any  state  having
jurisdiction,  this  being in  addition  to any other  remedy to which  they are
entitled at law or equity.

                  15. VALIDITY.  (a) The invalidity or  unenforceability  of any
provision of this Agreement shall not affect the validity or  enforceability  of
the other  provisions  of this  Agreement,  which shall remain in full force and
effect.

                  (b) In the event any court or other competent  authority holds
any provisions of this Agreement to be null, void or unenforceable,  the parties
hereto shall  negotiate in good faith the execution and delivery of an amendment
to this Agreement in order, as nearly as possible, to effectuate,  to the extent
permitted  by law,  the  intent  of the  parties  hereto  with  respect  to such
provision and the economic effects thereof.

                  (c) If for any  reason  any such  court or  regulatory  agency
determines  that BGE is not  permitted to acquire,  or PEPCO is not permitted to
repurchase  pursuant  to  Section 7, the full  number of shares of PEPCO  Common
Stock  provided  in  Section 1 hereof (as the same may be  adjusted),  it is the
express  intention  of PEPCO to allow  BGE to  acquire  or to  require  PEPCO to
repurchase  such  lesser  number  of shares as may be  permissible  without  any
amendment or modification hereof.

                  (d)  Each  party  agrees  that,  should  any  court  or  other
competent  authority  hold any provision of this  Agreement or part hereof to be
null, void or unenforceable,  or order any party to take any action inconsistent
herewith,  or not take any action required herein,  the other party shall not be
entitled  to specific  performance  of such  provision  or part hereof or to any
other remedy,  including but not limited to money damages,  for breach hereof or
of any other  provision  of this  Agreement or part hereof as the result of such
holding or order.

                  16. NOTICES.  All notices and other  communications  hereunder
shall be in writing and shall be deemed given if (a)  delivered  personally,  or
(b) if sent by overnight courier service (receipt confirmed in writing),  or (c)
if delivered by facsimile transmission with receipt confirmed), or (d) five days
after being mailed by registered or certified mail (return receipt requested) to
the parties in each case to the  following  addresses  (or at such other address
for a party as shall be specified by like notice):

                  A.  If to BGE, to:

                  By Mail:  P.O. Box 1475
                            Baltimore, MD  21203


                                      -15-






                  By Hand:  Liberty and Lexington Streets
                            Baltimore, MD  21201

                            Attention:  Charles W. Shivery
                                        Vice President and CFO
                                        Fax: (410) 234-5690

                                        David A. Brune, Esq.
                                        General Counsel
                                        Fax: (410) 234-5513

                  with a copy to:

                            Winthrop, Stimson, Putnam & Roberts
                            One Battery Park Plaza
                            New York, New York  10004-1490

                            Attention:  Stephen R. Rusmisel, Esq.
                                        Fax: (212) 858-1500

                  B.  If to PEPCO, to:

                  By Mail   1900 Pennsylvania Avenue, NW
                  and Hand: Washington, D.C.  20063

                            Attention:  Dennis R. Wraase
                                        Senior Vice President-
                                        Finance and Accounting
                                        Fax: (202) 331-6314

                                        William T. Torgerson
                                        Senior Vice President-
                                          Law & Governmental
                                          Relations, General Counsel
                                          and Secretary
                                        Fax: (202) 331-6314

                  with a copy to:

                            LeBoeuf, Lamb, Greene & MacRae, L.L.P.
                            125 West 55th Street
                            New York, New York  10019

                            Attention:  Douglas W. Hawes, Esq.
                                        Fax: (212) 424-8500




                                      -16-





                  and a copy to:

                            Covington & Burling
                            1201 Pennsylvania Avenue, N.W.
                            Washington, D.C.  20044

                            Attention:  George B. Reid, Jr., Esq.
                                        Fax: (202)662-6291


                  17.  GOVERNING LAW;  CHOICE OF FORUM.  This Agreement shall be
governed by and construed in  accordance  with the laws of the State of Maryland
applicable to agreements made and to be performed entirely within such State and
without regard to its choice of law principles.

                  18. INTERPRETATION.

                  (a) When  reference  is made in this  Agreement  to  Articles,
Sections or Exhibits, such reference shall be to an Article,  Section or Exhibit
of this Agreement, as the case may be, unless otherwise indicated.

                  (b) The  table of  contents  and  headings  contained  in this
Agreement are for reference purposes and shall not affect in any way the meaning
or interpretation of the Agreement.

                  (c) Whenever the words  "include,"  "includes," or "including"
are used in this  Agreement,  they shall be deemed to be  followed  by the words
"without limitation."

                  (d)  Whenever  "or"  is used in this  Agreement  it  shall  be
construed in the nonexclusive sense.

                  19.  COUNTERPARTS;  EFFECT.  This Agreement may be executed in
one or more counterparts,  each of which shall be deemed to be an original,  but
all of which shall constitute one and the same agreement.

                  20. AMENDMENTS;  WAIVER.  This Agreement may be amended by the
parties  hereto and the terms and  conditions  hereof  may be waived  only by an
instrument in writing signed on behalf of each of the parties hereto, or, in the
case of a waiver,  by an  instrument  signed  on  behalf  of the  party  waiving
compliance.

                  21.  EXTENSION OF TIME PERIODS.  The time periods for exercise
of certain rights under Sections 2, 6 and 7 shall be extended:

                  (a) to the extent necessary to obtain all regulatory approvals
for the exercise of such rights, and for the expiration of all statutory waiting
periods; and



                                      -17-





                  (b) to the  extent  necessary  to avoid  any  liability  under
Section 16(b) of the Exchange Act by reason of such exercise.






















                      THIS SPACE INTENTIONALLY LEFT BLANK




                                      -18-




                  IN WITNESS  WHEREOF,  the  parties  hereto  have  caused  this
Agreement to be executed by their respective duly authorized  officers as of the
date first above written.


                                             POTOMAC ELECTRIC POWER COMPANY


                                             /s/ EDWARD F. MITCHELL
                                             -----------------------------------
                                             Edward F.Mitchell
                                             Chairman of the Board and
                                               Chief Executive Officer

                                             BALTIMORE GAS AND ELECTRIC COMPANY


                                             /s/ CHRISTIAN H. POINDEXTER
                                             -----------------------------------
                                             Christian H. Poindexter
                                             Chairman of the Board and
                                               Chief Executive Officer



                                      -19-