Exhibit
10.20





AMENDMENT
NO. 1 TO SALARY CONTINUATION AGREEMENT





THIS AMENDMENT NO. 1 TO SALARY
CONTINUATION AGREEMENT (“Amendment No. 1”) is made, effective as of December 9,
2008, by and between GenVec, Inc., a Delaware corporation (the “Company”), and
Douglas J. Swirsky (“Executive”).





Recitals:





WHEREAS, Executive and the
Company previously entered into the Salary Continuation Agreement, effective as
of September 18, 2006 (the “Salary Continuation Agreement”); and




WHEREAS,Executive and the
Company desire to further amend the Salary Continuation Agreement to comply with
the requirements of Section 409A of the Internal Revenue Code of 1986, as
amended.




Agreement:




NOW, THEREFORE, in
consideration of the agreements contained herein and of such other good and
valuable consideration, the sufficiency of which Executive acknowledges, the
Company and Executive, intending to be legally bound, agree as
follows:




1.           A
new Section 3.4 shall be added to the Salary Continuation Agreement to read as
follows:





“3.4           Section 409A
Compliance.  Amounts payable other than those expressly payable
on a deferred or installment basis, will be paid as promptly as practical and,
in any event, within 21⁄2 months after the end of the year in which such amount
was earned.





Any
amount that the Executive is entitled to be reimbursed will be reimbursed as
promptly as practical and in any event not later than the last day of the
calendar year after the calendar year in which the expenses are incurred, and
the amount of the expenses eligible for reimbursement during any calendar year
will not affect the amount of expenses eligible for reimbursement in any other
calendar year.





If at the
time of separation from service (i) the Executive is a specified employee
(within the meaning of Section 409A and using the identification methodology
selected by the Company from time to time, and (ii) the Company  makes
a good faith determination that an amount payable by the Company to the
Executive constitutes deferred compensation (within the meaning of Section 409A)
the payment of which is required to be delayed pursuant to the six-month delay
rule set forth in Section 409A in order to avoid taxes or penalties under
Section 409A, then the Company will not pay such amount on the otherwise
scheduled payment date but will instead pay it in a lump sum on the first
business day after such six-month period together with interest for the period
of delay, compounded annually, equal to the prime rate (as published in the Wall
Street Journal) in effect as of the dates the payments should otherwise have
been provided.”










2.             The
provisions of this Amendment No. 1 may be amended and waived only with the prior
written consent of the parties hereto.  This Amendment No. 1 may be
executed and delivered in one or more counterparts, each of which shall be
deemed an original and together shall constitute one and the same
instrument.




3.           Except
as set forth in this Amendment No. 1, the Salary Continuation Agreement shall
remain unchanged and shall continue in full force and effect.




IN WITNESS WHEREOF, the
parties hereto have executed and delivered this Amendment No. 1 on the date
first written above.




GENVEC,
      INC.By: 
      /s/ Paul H.
      FischerName:
      Paul H. FischerTitle:
      President, CEOEXECUTIVEBy: 
      /s/ Douglas J.
      SwirskyDouglas
      J. Swirsky