Exhibit 10.9
                                  CERBCO, INC.

               SUPPLEMENTAL EXECUTIVE RETIREMENT INCOME AGREEMENT


THIS  AGREEMENT  is made by and between  CERBCO,  Inc.,  a Delaware  corporation
("CERBCO") and Robert F. Hartman ("Executive").

                                    RECITALS

         A.  This  Agreement's  purpose  is  to  provide  certain   supplemental
retirement  and  death  benefits  to  the  Executive  and  his   Beneficiary  in
consideration of his services to CERBCO and its subsidiaries.

         B. This Agreement has been approved on CERBCO's behalf by resolution of
CERBCO's Board of Directors.

         C. The benefits  provided  under this Agreement are to be determined by
aggregating  the  Executive's  employment  by CERBCO  and any one or more of its
subsidiaries  as though the  employment by these  companies  were  employment by
CERBCO,  and by aggregating the Executive's  salaries paid by CERBCO and any one
or more of its subsidiaries as though those salaries were all paid by CERBCO.

         NOW, THEREFORE, CERBCO and the Executive agree as follows:

         1.  Retirement  Income:  Beginning  on the first day of the month  next
following the month in which occurs the Executive's  Normal  Retirement Date or,
if later,  his  Termination  Date,  CERBCO shall pay to the  Executive a monthly
benefit (the  "Supplemental  Benefit") for the Executive's  life equal to 25% of
the Executive's Final Monthly Salary,  multiplied by the ratio (not to exceed 1)
of

         (i) his  completed  years (and any  fractional  year) of  employment by
CERBCO after 1992;

         (ii) the total number of years (and any fractional  year) of employment
by CERBCO  after  1992  that he would  have  completed  if he had  continued  in
employment to his Normal Retirement Date.

         If  the  Executive's  Termination  Date  occurs  prior  to  his  Normal
Retirement  Date, the Executive shall begin receiving his  Supplemental  Benefit
payments  as of the  first day of the month  next  following  the month in which
occurs his 62nd birthday or, if later, his Termination  Date,  without actuarial
reduction for early payment. In no event shall the Supplemental Benefit payments
begin prior to the later of the  Executive's  62nd  birthday or his  Termination
Date.

         2.       Death Benefit:

                  A.       After Retirement.

                  If  the  Executive   dies  after  the   commencement   of  his
Supplemental   Benefit   payments   but  before  he  has  received  180  monthly
Supplemental  Benefit  payments,  CERBCO shall pay to his  Beneficiary a monthly
Death  Benefit  beginning  on the  first  day of the month  next  following  the
Executive's  death and continuing  until the combined number of monthly payments
under this Agreement  received by the Executive and his Beneficiary  equals 180.
Each monthly Death Benefit payment under this paragraph 2A is to be equal to the
monthly  Supplemental  Benefit  payment that the  Executive was receiving at his
death.
                  B.       Before Retirement.

                  If the Executive dies before  commencement of his Supplemental
Benefit  payments,  CERBCO shall pay to his  Beneficiary a monthly Death Benefit
beginning on the first day of the month next following the Executive's death and
continuing  for 180  consecutive  monthly  payments.  Each monthly Death Benefit
payment under this paragraph 2B is to be equal to 25% of the  Executive's  Final
Monthly Salary.

         3. Funding:  CERBCO's  obligations under this Agreement are intended to
be  unfunded  for tax  purposes  and for  purposes  of  Title I of the  Employee
Retirement Income Security Act of 1974, as amended,  and shall not be secured in
any  manner.  No asset  of  CERBCO  shall be  placed  in trust or in  escrow  or
otherwise  physically or legally  segregated for the benefit of the Executive or
his  Beneficiary,  other than under a funding vehicle  intended not to cause the
plan to be funded  for such  purposes.  The  eventual  payment  of the  payments
described  in this  Agreement to the  Executive,  his  Beneficiary  or any other
person  shall not be secured to him or them by the  issuance  of any  negotiable
instrument  or other  evidence of  indebtedness  of CERBCO or its  subsidiaries.
Neither the Executive, his Beneficiary,  nor any other person shall be deemed to
have any property interest,  legal or equitable, in any specific asset of CERBCO
or its  subsidiaries,  and, to the extent that any person  acquires any right to
receive payments under this Agreement,  that right shall be no greater than, nor
shall it have any  preference  or  priority  over,  the rights of any  unsecured
general creditor.

         4.  Assignment:  No payments,  benefits or rights under this  Agreement
shall be subject  in any manner to  anticipation,  sale,  transfer,  assignment,
mortgage,  pledge,  encumbrance,  charge or  alienation  by the  Executive,  his
Beneficiary  or any other person who could or might  possibly  receive  payments
under this  Agreement.  In the event of any  attempted  assignment,  alienation,
encumbrance  or  transfer,  CERBCO  shall have no further  liability  under this
Agreement.

         5.  Amendment  and  Termination:  This  Agreement  may  be  amended  or
terminated at any time and in any respect by the written agreement of CERBCO and
the  Executive.  Notwithstanding  the foregoing  CERBCO's Board of Directors may
amend or terminate this Agreement at any time without the Executive's consent by
advance written notice  delivered to the Executive,  provided that the Board may
not  unilaterally:   (i)  reduce  or  modify  the  Executive's  accrued  benefit
determined  as of the date written  notice of the  amendment or  termination  is
received by the  Executive  or (ii) amend or  terminate  this  Agreement  in any
respect after a Change in Control has occurred.  The Executive's accrued benefit
as of any date is the  Supplemental  Benefit (and Death Benefit) that he and his
Beneficiary  would  receive,  under  this  Agreement,  if  that  date  were  his
Termination Date (but the Supplemental Benefit or Death Benefits payments are to
be deferred  until the earlier of the first day of the month next  following the
Executive's  death,  or the first day of the month next  following  the month in
which  occurs  his 62nd  birthday  or, if later,  his actual  Termination  Date,
without actuarial increase).

         6. Vesting and Forfeiture  for Cause:  The  Executive's  benefits under
this Agreement  (including  any benefits  payable to his  Beneficiary)  shall be
fully vested unless his  employment by CERBCO is terminated by CERBCO for Cause.
If the  Executive is terminated  for Cause,  all benefits  under this  Agreement
shall be  forfeited.  Termination  of the  Executive's  employment by CERBCO for
"Cause" means termination upon:

          (i) the willful and  continued  failure by Executive to  substantially
     perform his duties with CERBCO (other than any such failure  resulting from
     his  incapacity  due to physical or mental  illness) after a written demand
     for substantial  performance is delivered to Executive by CERBCO's Board of
     Directors,  which demand  specifically  identifies  the manner in which the
     Board  believes  that the  Executive  has not  substantially  performed his
     duties,

          (ii)  the  willful  engaging  by the  Executive  in  conduct  that  is
     demonstrably  and  materially  injurious  to  CERBCO  or its  subsidiaries,
     monetarily or otherwise, or

          (iii)  the  Executive's  conviction  of,  or plead of  guilty  or nolo
     contendere to, a felony in a court of competent jurisdiction in the U.S.

         No act or  failure  to act on the  Executive's  part  shall  be  deemed
"willful" unless done, or omitted to be done, by the Executive not in good faith
and without reasonable belief that his action or omission was in CERBCO's and/or
its subsidiaries' best interest.  The Executive shall not be deemed to have been
terminated  for Cause unless and until there shall have been  delivered to him a
copy of a  resolution  duly  adopted  by the  affirmative  vote of not less than
three-quarters  of the entire  membership of CERBCO's  Board at a meeting called
and held for that  purpose  (after  reasonable  notice to the  Executive  and an
opportunity  for the  Executive  and his counsel to be heard  before the Board),
finding  that in the good faith  opinion of the Board the  Executive  engaged in
conduct  described  under  clauses (i), (ii) or (iii) above and  specifying  the
particulars thereof.

         7. Other Retirement Benefits:  This Agreement supersedes any other plan
or agreement adopted prior to Agreement that provides retirement benefits to the
Executive,  except  (i) any  retirement  or  other  deferred  compensation  plan
intended to qualify  under  Section 401 or 403 of the  Internal  Revenue Code of
1986,  (ii) any plan or agreement that expressly  provides that its benefits are
not to be  superseded  by this  Agreement  and  (iii) any  nonqualified  plan or
agreement to which the  Executive has made  contributions  directly or by salary
reduction.

         8.  Construction:  This Agreement  shall be construed  according to the
laws of Maryland,  except where  superseded by Federal law. Use of the masculine
gender  includes the feminine  gender,  use of the  singular  case  includes the
plural,  and vice versa.  The invalidity of any portion of this Agreement  shall
not  invalidate  the remainder of the  Agreement,  which shall  continue in full
force and effect.  The  Supplemental  Benefits and the Death  Benefits are to be
payable  in the  same  manner  as  salary  payments  are made by  CERBCO  to its
executives.  All payments are subject to applicable  withholding and other taxes
required  by law.  CERBCO's  Board  of  Directors  shall  adopt  procedures  for
consideration of, and action with respect to, any claims made hereunder.

         9.  Successors:  This Agreement shall be binding upon the Executive and
CERBCO and their successors, assigns, heirs, executors and beneficiaries.

         10. Definitions:  When used in this Agreement, the following terms have
the meanings indicated below, unless a different meaning is clearly indicated by
the context:

         "Beneficiary"   means  the  person  or   persons   (who  may  be  named
contingently or  successively)  designated by the Executive from time to time to
receive the Death  Benefits as may be payable under this Agreement upon or after
the Executive's death. Any such beneficiary designation may be changed from time
to time by the Executive by filing a new  designation.  Each  designation by the
Executive will revoke all prior  designations by the Executive,  shall be in the
form  prescribed by CERBCO and will be effective only when filed in writing with
CERBCO during the Executive's  lifetime.  In the absence of a valid  Beneficiary
designation  or,  if  at  the  time  any  Death  Benefit  payment  is  due  to a
Beneficiary,  there is no living  Beneficiary  validly named by the Participant,
CERBCO shall pay any such benefit to the  Executive's  spouse,  if his spouse is
then  surviving  or, if the spouse is not  surviving,  or the  Executive  has no
spouse, to the Executive's estate.

         "Change in Control"  means the  occurrence  of either of the  following
events:  (1) a change of a nature  that would be  required  to be  reported,  by
persons or entities  subject to the reporting  requirements  of Section 13(d) of
the Securities and Exchange Act of 1934 (hereinafter called the "Exchange Act"),
in Schedule  13D of  Regulation  13D-G,  or any  successor  provisions  thereto,
promulgated  under the Exchange Act;  provided that a Change in Control shall be
deemed  to have  occurred  only if (a) any  "person"  (as  that  term is used in
Sections  13(d) and 14(d) of the  Exchange  Act) is or becomes  the  "beneficial
owner" (as defined in Rule 13d-3  issued under the  Exchange  Act),  directly or
indirectly,  of securities of CERBCO  representing  ten percent (10%) or more of
the combined voting power of CERBCO's then  outstanding  securities;  and (b) at
any time during the period of thirty-six (36) months subsequent to the ownership
change  described  above,  individuals  who  at the  beginning  of  such  period
constitute CERBCO's Board cease for any reason to constitute at least a majority
thereof  unless  the  election,  or the  nomination  for  election  by  CERBCO's
shareholders, of each new Director was approved by a vote of at least two-thirds
of the  Directors  still in office who were  Directors at the  beginning of such
thirty-six  (36) month period;  or (2) any "person",  as described  above, is or
becomes the "beneficial owner," directly or indirectly,  of securities of CERBCO
representing  forty  percent  (40%)  or more of the  combined  voting  power  of
CERBCO's then outstanding securities.

         "Final Monthly Salary" means the monthly  equivalent of the Executive's
highest combined rate of base annual salary earned by him from CERBCO and all of
its  subsidiaries,  before  any  salary  reductions  elected  by the  Executive;
provided,  however, that the Executive's "Final Monthly Salary" shall not exceed
the  amount of  $7,500,  increased  by 2%  (compounded  annually)  for each full
calendar  year  that  elapses  between  December  31,  1992 and the  Executive's
Termination Date.

         "Normal Retirement Date" means the Executive's 65th birthday.

         "Termination  Date" means the date that the  Executive's  employment by
the CERBCO group terminates for any reason, voluntarily or involuntarily.

IN WITNESS  WHEREOF,  the Executive and CERBCO have entered into this Agreement,
effective as of January 1, 1994.

ATTEST:                                CERBCO, INC.

Robert W. Erikson                      By: George Wm. Erikson
Assistant Secretary                    Its Chairman

[Corporate Seal]

WITNESS:                               EXECUTIVE

Robert W. Erikson                      Robert F. Hartman

<PAGE>


                       FIRST AMENDMENT TO THE CERBCO, INC.
               SUPPLEMENTAL EXECUTIVE RETIREMENT INCOME AGREEMENT
                             WITH ROBERT F. HARTMAN

         THIS  AGREEMENT  is  made  by and  between  CERBCO,  Inc.,  a  Delaware
corporation ("CERBCO") and Robert F. Hartman ("Executive").

         A. WHEREAS,  CERBCO and Executive entered into a Supplemental Executive
Retirement Income  Agreement,  effective as of January 1, 1994 (the "Agreement")
to provide certain  supplemental  retirement and death benefits to the Executive
and  his  beneficiary  in  consideration  of his  services  to  CERBCO  and  its
subsidiaries.

         B.  CERBCO  and the  Executive  now  desire to amend the  Agreement  to
substitute  split-dollar  death  benefit  arrangement  for  the  death  benefits
provided under the Agreement.

         NOW, THEREFORE, CERBCO and the Executive agree as follows:

         Subsection B. (titled "Before  Retirement") of Section 2 (titled "Death
Benefit") of the  Agreement  shall be deleted in its  entirety,  effective as of
July 1, 1997, and the following new Subsection 2.B is substituted therefor:

         B.       Before Retirement.

                  If  the  Executive  dies  before  the   commencement   of  his
         Supplemental  Benefit  payments  hereunder,  CERBCO  shall  pay  to his
         Beneficiary  a one-time,  lump sum Death Benefit in the amount of Seven
         Hundred  Thousand  Dollars  ($700,000.00) in lieu of all other benefits
         provided under this Agreement. The lump sum death benefit shall be paid
         to the  Executive's  beneficiary  within 90 days  after the date of the
         Executive's death.

         The Agreement,  as amended by the foregoing  change, is hereby ratified
and confirmed in all respects.

         IN WITNESS  WHEREOF,  the  Executive  and CERBCO have entered into this
Agreement effective as of July 1, 1997.

ATTEST                                 CERBCO, INC.

Robert F. Hartman                      By: George Wm. Erikson
Secretary                              Its: Chairman

[Corporate Seal]

WITNESS                                EXECUTIVE

Sharon E. Lavelle                      Robert F. Hartman