<PAGE>   1
                         Mahoning National Bancorp, Inc.
                                    Form 10-Q

                                   Item 6 (a)
                                 Exhibit 10 (g)

                     Change-In-Control Protective Agreement
                                Parker T. McHenry


<PAGE>   2


                    THE MAHONING NATIONAL BANK OF YOUNGSTOWN

                         -------------------------------

                               Guarantee Agreement

                        --------------------------------


         AGREEMENT entered into this 14th day May, 1997 (the "Effective Date"),
by and between The Mahoning National Bank of Youngstown (the "Bank") and Parker
T. McHenry (the "Employee").

         WHEREAS, the Employee is currently employed by the Bank in an executive
capacity, and has entered into a change-in-control protective agreement (the
"Company Agreement") with Mahoning National Bancorp, Inc. (the "Company"); and

         WHEREAS, the Board of Directors of the Bank has determined that it is
in the best interest of the Bank to enter into this Agreement in order to assure
continuity of the Bank's management through encouraging the long-term retention
of the Employee; and

         WHEREAS, the parties desire by this writing to set forth the Bank's
commitment to guarantee the Company's obligations under the Company Agreement.

         NOW, THEREFORE, it is AGREED as follows:

         1. The Bank shall be jointly and severally liable with the Company for
its obligations under the Company Agreement.

         2. This Agreement shall have a term that coincides with the term of the
Company Agreement (including any and all extensions thereunder), shall be
binding on any successors to the interest of the parties, shall be amended only
through a written instrument executed by both parties, and shall be governed by
the laws of the State of Ohio.

         IN WITNESS WHEREOF, the parties have executed this Agreement on the day
and year first written above.

ATTEST:                                THE MAHONING NATIONAL BANK
                                       OF YOUNGSTOWN

 /s/ Richard E. Davies                 By /s/ Daniel B. Roth
-----------------------------            ---------------------------------
Richard E. Davies                      By Daniel B. Roth
Secretary                                 Its duly authorized Director

WITNESS:

 /s/ Sandra L. Douglas                  /s/ Parker T. McHenry
-----------------------------          -----------------------------------
Sandra L. Douglas                       Parker T. McHenry
                                        Employee


<PAGE>   3





                     CHANGE-IN-CONTROL PROTECTIVE AGREEMENT

         THIS AGREEMENT entered into this 14th day of May, 1997, (the "Effective
Date") by and between, Mahoning National Bancorp, Inc. (the "Company"), and
Parker T. McHenry (the "Employee").

         WHEREAS, the Employee has heretofore been employed as an executive
officer of The Mahoning National Bank of Youngstown (the "Bank"), and thereby
has directly contributed to the financial success and operational stability of
the Company; and

         WHEREAS, the Company deems it to be in the best interests of its
stockholders to enter into this Agreement as additional incentive to the
Employee to continue to serve in such capacity; and

         WHEREAS, the parties desire by this writing to set forth their
understanding as to their respective rights and obligations in the event a
change of control occurs with respect to the Bank or the Company.

         NOW, THEREFORE, the undersigned parties AGREE as follows:

         1. DEFINED TERMS

            When used anywhere in the Agreement, the following terms shall have
the meaning set forth herein.

         (a) "Beneficiary" shall mean the person or persons as stated in the
last designation of beneficiary concerning this Agreement signed by the Employee
and filed with Company, and if not, then the personal representative of the
Employee.

         (b) "Change in Control" shall mean any one of the following events: (i)
the acquisition of ownership, holding or power to vote more than 30% of the
Bank's or the Company's voting stock, (ii) the acquisition of the ability to
control the election of a majority of the Bank's or the Company's directors,
(iii) the acquisition of a controlling influence over the management or policies
of the Bank or the Company by any person or by persons acting as a "group"
(within the meaning of Section 13(d) of the Securities Exchange Act of 1934), or
(iv) during any period of two consecutive years, individuals (the "Continuing
Directors") who at the beginning of such period constitute the Board of
Directors of the Bank or the Company (the "Existing Board") cease for any reason
to constitute at least two-thirds thereof, provided that any individual whose
election or nomination for election as a member of the Existing Board was
approved by a vote of at least two-thirds of the Continuing Directors then in
office shall be 

<PAGE>   4

considered a Continuing Director. Notwithstanding the foregoing, in the case of
(i), (ii) and (iii) hereof, ownership or control of the Bank by the Company
itself shall not constitute a Change in Control. For purposes of this paragraph
only, the term "person" refers to an individual or a corporation, partnership,
trust, association, joint venture, pool, syndicate, sole proprietorship,
unincorporated organization or any other form of entity not specifically listed
herein.

             (c) "Code" shall mean the Internal Revenue Code of 1986, as amended
from time to time, and as interpreted through applicable rulings and regulations
in effect from time to time.

             (d) "Code Section 280G Maximum" shall mean the product of 2.99 and
the Employee's "base amount" as defined in Code Section 280G(b)(3).

             (e) "Good Reason" shall mean any of the following events, which has
not been consented to in advance by the Employee in writing: (i) the requirement
that the Employee move his or her personal residence, or perform his or her
principal executive functions, more than thirty (30) miles from his primary
office as of the date of the Change in Control; (ii) a material reduction in the
Employee's base compensation as in effect on the date of the Change in Control
or as the same may be increased from time to time; (iii) the failure by the Bank
or the Company to continue to provide the Employee with compensation and
benefits provided for on the date of the Change in Control, as the same may be
increased from time to time, or with benefits substantially similar to those
provided under any of the employee benefit plans in which the Employee now or
hereafter becomes a participant, or the taking of any action by the Bank or the
Company which would directly or indirectly reduce any of such benefits or
deprive the Employee of any material fringe benefit enjoyed at the time of the
Change in Control; (iv) the assignment to the Employee of duties and
responsibilities materially different from those normally associated with his or
her position; (v) a failure to elect or reelect the Employee to the Board of
Directors of the Bank or the Company, if the Employee is serving on such Board
on the date of the Change in Control; (vi) a material diminution or reduction in
the Employee's responsibilities or authority (including reporting
responsibilities) in connection with employment with the Bank or the Company; or
(vii) a material reduction in the secretarial or other administrative support of
the Employee.

             (f) "Just Cause" shall mean, in the good faith determination of the
Bank's Board of Directors, the Employee's personal dishonesty, willful
misconduct, breach of fiduciary duty involving personal profit, intentional
failure to perform stated duties, willful violation of any law, rule or
regulation (other than traffic violations or similar offenses) or final
cease-and-desist order, or material breach of any provision of this Agreement.
The Employee shall have no right to receive compensation or other benefits for
any period after termination for Just Cause. No act, or failure to act, on the
Employee's part shall be considered "willful" unless the Employee has acted, or
failed to act, with an absence of good faith and without a reasonable belief
that such action or failure to act was in the best interest of the Bank and the
Company.


<PAGE>   5

            (g) "Protected Period" shall mean the period that begins on the
date six months before a Change in Control and ends on the later of the first
annual anniversary of the Change in Control or the expiration date of this
Agreement.

            (h) "Trust" shall mean a grantor trust designed in accordance with
Revenue Procedure 92-64 and having a trustee independent of the Bank and the
Company,

         2. TRIGGER EVENTS

         The Employee shall be entitled to receive the severance benefits set
forth in Section 3 of this Agreement in the event that (i) the Employee
voluntarily terminates employment either for any reason within 30 days of a
Change in Control, (ii) the Employee voluntarily terminates employment within 90
days of an event that both occurs during the Protected Period and constitutes
Good Reason, or (iii) the Bank, the Company, or their successor(s) in interest
terminate the Employee's employment for any reason other than Just Cause during
the Protected Period.

         3. SEVERANCE BENEFITS

         If the Employee becomes entitled to receive severance benefits pursuant
to Section 2 hereof, the Company shall BOTH provide the Employee with the
opportunity, until the Employee first begins to participate in Medicare, to
purchase, at the Employee's own expense which shall not exceed applicable COBRA
rates, family medical and dental insurance under any group health plans that the
Bank or the Company maintains for its employees, AND pay the Employee (or the
Employee's Beneficiary in the event of the Employee's death before all required
payments have been made under this Agreement) a severance benefit, for 24 months
after termination of employment, in an amount equal to the Employee's highest
monthly salary in effect between the date that the Protected Period begins and
the date of the Change in Control. In no event, however, will the present value
of these severance payments exceed the difference between the Code  Section 280G
Maximum and the sum of any other "parachute payments" as defined under Code
Section 280G(b)(2) that the Employee receives on account of the Change in 
Control. Said payments shall commence within ten days of the later of the date
of the Change in Control and the Employee's last day of employment with the
Bank or the Company.

         In the event that the Employee and the Company agree that the Employee
has collected an amount exceeding the Code  Section 280G Maximum, the parties 
may jointly agree in writing that such excess shall be treated as a loan AB
INITIO which the Employee shall repay to the Company, on terms and conditions
mutually agreeable to the parties, together with interest at the applicable
federal rate provided for in Section 7872(f)(2)(B) of the Code.


<PAGE>   6

         4. FUNDING OF GRANTOR TRUST UPON CHANGE IN CONTROL

         Notwithstanding any other provision of this Agreement that may be
contrary or inconsistent herewith, not later than ten (10) business days after a
Change in Control, the Company shall (i) establish a grantor trust (the "Trust")
that is designed in accordance with Revenue Procedure 92-64 and has a trustee
(the "Trustee") independent of the Company and any successor to their interest,
(ii) deposit in the Trust an amount equal to the present value of all benefits
that may become payable under this Agreement, and (iii) provide the Trustee with
an irrevocable written direction both to hold all Trust assets and any
investment return thereon in a segregated account for the benefit of the
Employee, and to follow the procedures set forth in the next paragraph as to the
payment of amounts from the Trust.

         At any time after a Change in Control, the Employee may provide the
Trustee with a written affidavit (the "Affidavit") in which the Employee attests
that he has terminated employment with the Company or any successor to its
interest, and has become entitled to commence receiving the monthly benefit
payments (required by Section 3 hereof). The Affidavit shall also specify the
amount of each such monthly payment to be made from the Trust. On the first
business day of the month following the Trustee's receipt of the Affidavit, the
Trustee shall commence paying the Employee, in immediately available funds, the
monthly benefit specified in the Affidavit, and shall send a copy of it to the
Company via overnight and registered mail (return receipt requested). Upon the
receipt of the Employee's written release of all claims under this Agreement,
the Trustee shall pay to the Company any remaining assets in the Trust. The
Company shall pay any and all expenses associated with maintaining the Trust,
and shall hold the Trustee harmless from any liability for making the payments
required hereunder.

         5. TERM OF THE AGREEMENT. This Agreement shall remain in effect for the
period commencing on the Effective Date and ending on the earlier of (i) the
date 36 months after the Effective Date, and (ii) the date on which the Employee
terminates employment with the Bank; provided that the Employee's rights
hereunder shall continue following the termination of this employment with the
Bank or the Company under any of the circumstances described in Section 2
hereof. Additionally, on each annual anniversary date from the Effective Date,
the term of this Agreement shall automatically be extended for an additional
one-year period beyond the then effective expiration date unless the Board of
Directors of the Company determines to the contrary in a duly adopted resolution
AND delivers a certified copy of the resolution to the Employee BEFORE the date
on which the Agreement would otherwise renew.

         6. EXPENSE REIMBURSEMENT.

            In the event that any dispute arises between the Employee and the 
Bank or the Company as to the terms or interpretation of this Agreement, whether
instituted by formal legal 

<PAGE>   7

proceedings or otherwise, including any action that the Employee takes to
enforce the terms of this Agreement or to defend against any action taken by the
Bank or the Company, the Employee shall be reimbursed for all costs and
expenses, including reasonable attorneys' fees, arising from such dispute,
proceedings or actions, provided that the Employee shall obtain a final
judgement in favor of the Employee in a court of competent jurisdiction or in
binding arbitration under the rules of the American Arbitration Association.
Such reimbursement shall be paid within ten days of Employee's furnishing to the
Bank and the Company written evidence, which may be in the form, among other
things, of a cancelled check or receipt, of any costs or expenses incurred by
the Employee.

         7. SUCCESSORS AND ASSIGNS.

            (a) This Agreement shall inure to the benefit of and be binding upon
any corporate or other successor of the Company which shall acquire, directly or
indirectly, by merger, consolidation, purchase or otherwise, all or
substantially all of the assets or stock of the Bank or Company.

            (b) Since the Company is contracting for the unique and personal
skills of the Employee, the Employee shall be precluded from assigning or
delegating his rights or duties hereunder without first obtaining the written
consent of the Company.

         8. AMENDMENTS. No amendments or additions to this Agreement shall be
binding unless made in writing and signed by all of the parties, except as
herein otherwise specifically provided.

         9. APPLICABLE LAW. Except to the extent preempted by Federal law, the
laws of the State of Ohio shall govern this Agreement in all respects, whether
as to its validity, construction, capacity, performance or otherwise.

         10. SEVERABILITY. The provisions of this Agreement shall be deemed
severable and the invalidity or unenforceability of any provision shall not
affect the validity or enforceability of the other provisions hereof.

         11. ENTIRE AGREEMENT. This Agreement, together with any understanding
or modifications thereof as agreed to in writing by the parties, shall
constitute the entire agreement between the parties hereto.

         IN WITNESS WHEREOF, the parties have executed this Agreement on the day
and year first hereinabove written.

<PAGE>   8

ATTEST:                                       MAHONING NATIONAL BANCORP, INC.

 /s/ Richard E. Davies                        By: /s/ Daniel B. Roth
--------------------------                       ------------------------------
Richard E. Davies                             By: Daniel B. Roth
Its Secretary                                     Its duly authorized Director

WITNESS:

 /s/ Sandra L. Douglas                            /s/ Parker T. McHenry
--------------------------                       ------------------------------
Sandra L. Douglas                                 Parker T. McHenry
                                                  Employee