EMPLOYMENT TERMINATION AND SEVERANCE AGREEMENT
 
          THIS EMPLOYMENT TERMINATION AND SEVERANCE AGREEMENT (this "Termination
Agreement")  is entered  into as of January  15,  1998,  by and  between  Aronex
Pharmaceuticals,  Inc. ("Aronex"), and James M. Chubb, an individual residing at
183 Bristol Bend Circle, The Woodlands, Texas 77382 ("Employee").
 
          WHEREAS,  Aronex and Employee have previously  entered into an Amended
and  Restated  Employment  Agreement  dated  January 15,  1996 (the  "Employment
Agreement");
 
          WHEREAS,  Employee  intends to resign from his employment  with Aronex
effective January 15, 1998 (the "Effective Date "); and
 
          WHEREAS,  Aronex and  Employee now wish to  terminate  the  Employment
Agreement and release each other from any claims  arising  thereunder  effective
upon the Effective Date;
 
          NOW,  THEREFORE,  in  consideration  of the  premises  and the  mutual
covenants contained herein, the parties hereto agree as follows:
 
          1. Termination. The Employment Agreement is terminated effective as of
the  Effective  Date and none of the parties  shall have any  further  rights or
obligations  thereunder  after the Effective Date except as expressly  specified
herein.
 
          2. Severance. For and in consideration of Employee's execution of this
Termination  Agreement,  Aronex will,  subject to the further provisions of this
Termination Agreement,  (i) pay Employee monthly payments of $19,583 (Employee's
current  Base  Salary)  for the  period  beginning  as of January  15,  1998 and
continuing  through  January  15,  1999,  payable  as and  when  Employee  would
otherwise  be paid his salary  under  Section  4.1 of the  Employment  Agreement
(collectively,  the "Severance Payments"),  (ii) continue to pay through January
15, 1999 the premiums required for Employee's  continued  coverage under (A) the
Company's group medical and dental plans for Employee and Employee's family, (B)
the disability  insurance presently maintained by the Company for the benefit of
Employee and (C) the life insurance presently  maintained by the Company for the
benefit of Employee and Employee's  beneficiaries,  (iii) provide  Employee with
basic  outplacement  services  (consisting  of office  space and  administrative
assistance) through Lee Hecht Harrison or a reasonably  equivalent  outplacement
services  provider selected by Aronex,  (iv) continue to pay Employee's  regular
annual  membership  dues to  maintain  Employee's  membership  at The  Woodlands
Country Club through  January 15, 1999,  (v) extend (and hereby does extend) the
period  during which  options  granted to Employee  under  Aronex's  Amended and
Restated  1989 Stock Option Plan (the  "Plan") may vest until  January 31, 2000,
with the same effect under the terms of such options as if Employee  remained an
employee of Aronex  through such date,  and (vi) extend (and hereby does extend)
the period during which Employee may exercise  options granted to Employee under
the Plan,  to the extent  such  options are vested as of the  Effective  Date or
become vested pursuant to the preceding  clause of this  Termination  Agreement,
until  February 28, 2000.  The  Severance  Payments  shall not be subject to any
reduction  or right of offset as a result of  Employee's  employment  by another
entity during the term of this Termination Agreement, and the Severance Payments
and the benefits  contemplated  by clause (ii) above shall not be subject to any
reduction  or right of  offset as a result of  Employee's  death or  disability,
provided in each such case that  Employee has complied with the terms of Section
3 hereof and the terms of Section 5 hereof and the agreements referenced therein
(insofar as such terms of Section 5 and the agreements referenced therein relate
to  Employee's   obligations   regarding   confidentiality,   nondisclosure  and
inventions).

<PAGE>

          3. Release of Aronex by Employee.  (a) Employee, on behalf of himself,
his heirs, beneficiaries and personal representatives,  hereby releases, acquits
and forever  discharges Aronex,  its of officers,  employees,  former employees,
stockholders,  directors,  agents and assigns,  and all other persons,  firms or
corporations  in control of, under the  direction  of, or in any way  associated
with Aronex  (collectively,  the "Aronex  Affiliates"),  of and from all claims,
charges, complaints, liabilities,  obligations, promises, agreements, contracts,
damages, actions, causes of action, suits, accrued benefits or other liabilities
of any kind or character,  whether known or hereafter discovered,  arising from,
growing out of, or in any way connected with or related to Employee's employment
with, and/or  termination of employment from, Aronex and the Aronex  Affiliates,
including,   but  not  limited   to,   allegations   of  wrongful   termination,
discrimination,   breach  of  contract,   intentional  infliction  of  emotional
distress,  invasion  of privacy,  promissory  estoppel,  whistleblowing,  fraud,
termination  for refusal to perform an illegal  act,  defamation,  any action in
tort or contract,  any action for unpaid  wages,  attorney's  fees,  or punitive
damages,  and any violation of any federal,  state, or local law,  including but
not limited to, any  violation of Title VII of the Civil Rights Acts of 1964 and
1991,  as amended,  42 U.S.C.  2000e et seq.,  the Civil Rights Act of 1866,  42
U.S.C. 1981 et seq., the Equal Pay Act, 29 U.S.C.  206, the Employee  Retirement
Income  Security Act of 1974, as amended  (ERISA),  29 U.S.C.  1001 et seq., the
Americans  with  Disabilities  Act,  42 U.S.C.  12101 et.  seq.,  the Fair Labor
Standards  Act, as amended,  29 U.S.C.  621 et seq., the Age  Discrimination  in
Employment Act, as amended,  29 U.S.C. 621 et seq., the Family and Medical Leave
Act of 1993,  29 U.S.C.  2601 et seq.,  the Worker  Adjustment  and  Restraining
Notification Act (WARN),  29 U.S.C.  2101 et seq., the Texas Commission on Human
Rights Act, as amended,  Texas Labor Code 21.001 et seq.,  the Texas Payday Act,
Texas Labor Code 61.001 et seq., the Texas Workers' Compensation Statute,  Texas
Labor Code 451.001 et seq.  and any other civil  rights act, and all  amendments
made to any such laws from time to time,  provided  that the  foregoing  release
shall not apply to the  express  obligations  of Aronex  under this  Termination
Agreement.

          (b) Employee  agrees not to commence any legal  proceeding  or lawsuit
against Aronex or any Aronex  Affiliate  arising out of or based upon Employee's
employment with Aronex or any Aronex  Affiliate or because of the termination of
Employee's employment with Aronex or any Aronex Affiliate.

          (c) The  consideration  cited above and the promises  contained herein
are made for the  purpose  of  purchasing  the  peace of Aronex  and the  Aronex
Affiliates  and are not to be  construed  as an  admission  of  liability  or as
evidence  of  unlawful  conduct  by Aronex  or any  Aronex  Affiliate,  all such
liability being herein expressly denied.

          (d) Employee  voluntarily accepts the Severance Payments as sufficient
payment for the full, final and complete release stated herein,  and agrees that
no other promises or representations  have been made to Employee by Aronex or an
Aronex  Affiliate or any other person  purporting to act on the behalf of Aronex
or an Aronex Affiliate, except as expressly stated herein.

          (e)  Employee  understands  that this is a full,  complete,  and final
release of Aronex and the  Aronex  Affiliates.  As  evidenced  by the  signature
below,  Employee  expressly  promises  and  represents  to Aronex and the Aronex
Affiliates that he has completely read this Agreement and understands its terms,
contents,  conditions,  and effects.  Employee stipulates and agrees that Aronex
and Aronex  Affiliates do not owe Employee anything in addition to what Employee
will be receiving pursuant to Section 2 of this Termination Agreement.


     (f)   Employee   hereby   waives  all  rights  to  recall,   reinstatement,
reemployment and past or future wages from Aronex and the Aronex  Affiliates and
further,   acknowledges   that   Employee  is  not  entitled  to  any  continued
participation  in, or benefits under,  any employee benefit plan or compensation
program of Aronex or any Aronex Affiliate,  including,  without limitation,  any
profit, bonus or commission arrangement,  the Plan, the Employment Agreement and
any other  employment  agreement  (whether  written or oral)  with the  Company,
except as may otherwise be required by ERISA or as otherwise expressly set forth
herein.
 
<PAGE>

          4. Release of Employee by Aronex.  Aronex, on behalf of itself and the
Aronex Affiliates, hereby releases, acquits and forever discharges Employee, his
heirs,  beneficiaries  and  personal  representatives,  of and from all  claims,
charges, complaints, liabilities,  obligations, promises, agreements, contracts,
damages, actions, causes of action, suits, accrued benefits or other liabilities
of any kind or character,  whether known or hereafter discovered,  arising from,
growing out of, or in any way connected with or related to Employee's employment
with, and/or  termination of employment from, Aronex and the Aronex  Affiliates,
provided that the foregoing  release shall not apply to the express  obligations
of Employee under this  Termination  Agreement or as  contemplated  by Section 5
below.
 
          5. Acknowledgment of Remaining Obligations Under Employment Agreement.
Employee   acknowledges   that   he   is   subject   to   agreements   regarding
confidentiality,  nondisclosure,  inventions and noncompetition  pursuant to the
provisions   of  Sections  8  and  9  of  the   Employment   Agreement  and  the
confidentiality  and  non-disclosure   agreement   referenced   therein,   which
provisions  and  obligations  remain in full  force and  effect  following  this
Termination Agreement.
 
          6.  Statements to Third  Parties.  Aronex agrees that it will not make
any  statements to third  parties which are intended to disparage,  discredit or
injure the  reputation  of Employee.  Employee  agrees that he will not make any
statements to third parties which are intended to disparage, discredit or injure
the reputation of Aronex or any Aronex Affiliate.
 
          7. No Assignment of Claims.  Employee  hereby warrants that he has not
assigned,  transferred  or conveyed at any time to any  individual or entity any
alleged right,  claim or cause of action against Aronex or any Aronex Affiliate.
Employee  agrees to and does  hereby  indemnify  and hold  Aronex and the Aronex
Affiliates  harmless from any claims,  liabilities,  damages,  demands,  losses,
costs,  debts and  causes of action  whatsoever,  including  without  limitation
attorney's fees, whether known or unknown,  which may be asserted by parties for
breach of the foregoing warranty.

          8. No Duress,  Etc.  Employee  hereby  warrants  to Aronex that he has
completely read this Termination  Agreement prior to executing it, and has had a
reasonable  period  of time  within  which to  consider  this  Agreement  and to
understand its terms, contents, conditions and effects and has entered into this
Termination  Agreement knowingly and voluntarily.  Employee  understands that he
has the right to consult an  attorney of his choice and  represents  that he has
consulted with an attorney. Employee states that he is not presently affected by
any disability which would prevent him from knowingly and voluntarily  executing
this Termination Agreement, and further states that the promises made herein are
not made under duress,  coercion or undue influence.  Employee  understands that
Employee  has  twenty-one  days  within  which  to  consider  and  execute  this
Agreement,  and that this  Agreement  is  revocable  by Employee for a period of
seven days  following  the date of  execution of this  Agreement,  and if not so
revoked,  this Agreement will automatically  become effective and enforceable on
the eighth day following the date of its execution.
<PAGE>

          9.  Amendment.  This  Termination  Agreement  may  not be  amended  or
modified  in any  respect  except by an  agreement  in writing  executed  by the
parties in the same manner as this Agreement.

          10. Successors.  This Termination  Agreement shall be binding upon and
shall  inure to the  benefit of and be  enforceable  by each of the  parties and
their respective successors and assigns.

          11. Invalid Provisions. If any provision of this Termination Agreement
is held to be  illegal,  invalid or  unenforceable  under  present or future law
effective during the term hereof, such provision shall be fully severable.  This
Termination  Agreement  shall be  construed  and  enforced  as if such  illegal,
invalid or  unenforceable  provision  had never  comprised a part hereof and the
remaining portions hereof shall remain in full force and effect and shall not be
effected by the illegal,  invalid or unenforceable provision or by its severance
here  from.  Furthermore,  in lieu of such  illegal,  invalid  or  unenforceable
provision,  there  shall be  added  automatically,  as part of this  Termination
Agreement,   a  provision   similar  in  terms  to  such  illegal,   invalid  or
unenforceable provision as may be possible and be legal, valid and enforceable.

          12.  Descriptive  Headings.  The  descriptive  headings of the several
sections of this  Termination  Agreement are inserted for  convenience  only and
shall not control or affect the meaning or construction of any of the provisions
hereof.

          13. Governing Law. This Termination Agreement shall be governed by and
construed and enforced in accordance  with the laws of the State of Texas.  

          14. Entire  Agreement.  This  Termination  Agreement  constitutes  the
entire  agreement  between the parties hereto with respect to the subject matter
of this Termination Agreement and supersedes and is in full substitution for any
and all prior agreements and understandings whether written or oral between said
parties relating to the subject matter of this Termination Agreement.


          IN WITNESS  WHEREOF,  the parties have duly executed this  Termination
Agreement effective as of the date first above written.

                                             EMPLOYEE:
                                             James M. Chubb



                                            
                                             ARONEX PHARMACEUTICALS, INC.




                                             By:
                                             Geoffrey Cox
                                             Chairman of the Board and
                                             Chief Executive Officer