<PAGE>

                                  EXHIBIT 10(o)

                              EMPLOYMENT AGREEMENT

     This Employment Agreement is made as of September 1, 2001, at Groveport,
Ohio, between Pinnacle Data systems, Inc., an Ohio corporation (the "Company"),
and C. Robert Hahn (the "Employee"), who hereby agree as follows:

     [sect]1.     Employment.  The Company hereby renews and continues the
                  ----------
Employee's employment, and the Employee hereby accepts such employment renewal
and continuation by the company, on the terms and subject to the conditions set
forth in this agreement.

     [sect]2.     Term of Employment.  The term of this Employee's employment as
                  ------------------
renewed pursuant to this agreement shall begin as of the date of this agreement
and shall terminate, unless sooner terminated in accordance with the provisions
of [sect]6, below, on September 1, 2003. The term of employment under this
Agreement shall be automatically extended for successive one (1) year periods
commencing on each September 1 each year unless either party shall have given
written notice to the other party no later than the preceding August 15 of his
or its intention that the term hereof not be extended beyond its then current
term.

     [sect]3.     Services.  The Employee shall be employed as Vice President of
                  --------
the Service Group, and will at all times faithfully, industriously, and to the
best of his ability, experience and talents, perform all of the duties that may
be required of and from him pursuant to the express and implicit terms hereof
and such other duties as may be assigned to him from time to time by the
Company, acting by and through its Chief Executive Officer ("CEO") or its Board
of Directors. The Employee shall report to the Company's CEO and President.

     [sect]4.     Compensation.  During the term of his employment  pursuant to
                  ------------
this agreement, the Employee shall be entitled to receive the following
compensation:

                  (a)     Salary.  An annual base salary of $125,000 (one
                          ------
         hundred twenty-five thousand) per year.

                  (b)     Bonus. An incentive cash bonus equal to a percentage
                          -----
         of the pre-tax net income of the company (or based upon other factors
         deemed appropriate by the CEO and President) for each fiscal year
         ending during the term of employment under this agreement (calculated
         prior to the deduction of the bonus). The bonus percentage or other
         factors for each year will be determined by the CEO and President or
         the Board or Directors or its Compensation Committee no later than
         March of that year.

                                      -1-

<PAGE>

                  The base salary will be payable in accordance with the
Company's general policies for payment of compensation to salaried personnel.
The bonus will be payable after the end of each fiscal year of the Company as
soon as practical after the Company's independent auditors have completed the
year-end audit of the Company's financial statements for such year.

     [sect]5.     Fringe  Benefits.  During the term of employment  pursuant
                  ----------------
to this agreement, the Employee shall be entitled to the following fringe
benefits:

                  (a)     Vacation.  Employee is entitled to 20 days of Paid
                          --------
     Time Off ("PTO"). PTO will be taken pursuant to the Company's PTO policy as
     amended or changed from time to time.

                  (b)     Disability Payments.  If at any time during the term
                          -------------------
     of employment the Employee shall be unable to perform his duties
     hereunder for a period not to exceed six (6) months, Employee shall
     nonetheless be entitled to receive any compensation the Employee would
     otherwise be entitled to pursuant to [sect]4(a), above, during the period
     of such disability, provided, however, that his "disability" be documented
     by a competent medical doctor selected to examine the Employee at the
     request of the disinterested Board of Directors, which examination
     expense shall be borne by the Employer. In the event said disability
     shall continue for a period greater than six (6) months, then it shall be
     considered a "long-term disability", the Employee shall no longer be
     entitled to receive any compensation under [sect]4 of this agreement
     during the remaining period of such disability, and upon the vote of a
     majority of the disinterested Directors, said Employee shall be terminated
     in consonance with the provisions of [sect]6 hereof as if said disabled
     Employee had voluntarily terminated his services hereunder.

                  (c)     Executive Development.  The Employee shall be required
                          ---------------------
     to attend a personal executive development or experiential learning
     seminar of his choice for up to three days during each year of the
     employment term, with spousal accommodations.

                  (d)     Other Fringe Benefits.  The Employee shall be entitled
                          ---------------------
     to such other fringe benefits and perquisites as may be provided
     generally for the Company's executive management pursuant to policies
     established or changed from time to time by the Board.

                                      -2-

<PAGE>

     [sect]6.     Termination of Employment.  Notwithstanding the provisions
                  -------------------------
     of [sect]3 above, the Agreement may be terminated by either party as
     follows:

                  (a)     By the Employee within six months after a Change in
     Control of the Company (as defined below); provided that after such Change
     in Control of the Company, the Employee's base salary or other benefits
     have been reduced or the Employee's authority or responsibilities have been
     significantly reduced. If the Employee terminates his employment pursuant
     to this provision, he shall be entitled to receive his salary and benefits
     to the date of termination, any bonus for such year to which he would
     otherwise be entitled, prorated for the portion of the year during which
     the Employee was employed, and a payment from the Company, in a lump sum,
     in an amount equal to one year's base salary.

                  (b)     By the Company immediately upon the occurrence of
     cause (as defined below) or at any time thereafter. For purposes of this
     agreement, "cause" shall mean the Employee's failure to operate the
     Company's business in accordance with the policies, programs, budgets,
     procedures, and directions established from time to time by the Board or
     the CEO, the Employee's failure fully to perform and observe all
     obligations and conditions to be performed and observed by the Employee
     under this agreement, or the Employee's dishonesty, conviction of a crime
     (other than minor traffic offenses), habitual drunkenness, using illegal
     drugs, embezzlement, conflict of interest, willful insubordination, or
     neglect of duty. If the Company terminates the Employee's employment
     pursuant to this provision, he shall be entitled to receive only his base
     salary through the date of termination.

                  (c)     By the Company with or without cause upon giving not
     less than 60 days advance written notice prior to the date of termination.
     If the Company terminates the Employee's employment pursuant to this
     provision, he shall be entitled to receive his salary to the date of
     termination, any bonus for such year to which he would otherwise be
     entitled, prorated for the portion of the year during which the Employee
     was employed, and a payment from the Company, in a lump sum, in an amount
     equal to one year's base salary.

                                      -3-

<PAGE>

                  (d)     By the Company if the Employee is under a long-term
     disability, at which time the Employee will receive any amounts due to
     him under a long-term disability policy of the Company, if any, and due
     to him pursuant to [sect]5(b). For purposes of this agreement, the term
     "long-term disability" shall have the same meaning as set forth in
     [sect]5(b) and employment may be terminated as provided in [sect]5(b).

     For purposes of this agreement, a Change in Control shall be deemed to
     occur:

                          (i)    When any "person" as defined in [sect].3(a)(9)
                  of the Securities Exchange Act of 1934 (the "Exchange Act")
                  and as used in [sect][sect]13(d) and 14(d) thereof, including
                  a "group" as defined in [sect]13(d) of the Exchange Act, but
                  excluding the Company and any subsidiary and any employee
                  benefit plan sponsored or maintained by the Company or any
                  subsidiary (including any trustee of such plan acting as
                  trustee), directly or indirectly, becomes the "beneficial
                  owner" (as defined in Rule 13d-3 under the Exchange Act, as
                  amended from time to time), of securities of the Company
                  representing 30% or more of the combined voting power of the
                  Company's then outstanding securities;

                          (ii)    When, during any period of 24 consecutive
                  months during the existence of this agreement, the individuals
                  who, at the beginning of such period, constitute the Board
                  (the "Incumbent Directors") cease for any reason other than
                  death to constitute at least a majority thereof; provided,
                  however, that a director who was not a director at the
                  beginning of such 24-month period shall be deemed to have
                  satisfied such 24-month requirement (and be an Incumbent
                  Director) if such director was elected by, or on the
                  recommendation of or with the approval of, at least
                  two-thirds of the directors who then qualified as
                  Incumbent Directors either actually (because they were
                  directors at the beginning of such 24-month period) or by
                  prior operation of this paragraph; or

                         (iii)    Upon the occurrence of a transaction requiring
                  shareholder approval for the acquisition of the Company by an
                  entity other than the Company or a subsidiary through purchase
                  of assets, by merger, or otherwise.

                                      -4-

<PAGE>

     [sect]7.     Noncompetition; Nondisclosure; Ownership of Developments.  In
                  --------------------------------------------------------
consideration of the substantial increase in base salary and other benefits
provided to the Employee, the Company and the Employee agree as follows:

                  (a)     During the term of the Employee's employment by the
     Company, pursuant to this agreement or otherwise, and for a period of
     one year immediately after termination of such employment, the Employee
     shall not directly or indirectly:

                          (i)     Engage in or participate in any business
                  similar to the business of the Company within the United
                  States and within any other country in which the Company
                  has engaged in business during the term of the Employee's
                  employment by the Company; or

                          (ii)    Sell or perform the same or similar services
                  or products as then provided by the Company to, or
                  solicit, any of the Company's present customers or
                  accounts or persons or businesses which were customers or
                  accounts within three years preceding the Employee's
                  termination of employment with the Company; or

                          (iii)   Promote or assist, financially or otherwise,
                  any person, firm, association, corporation, or other entity
                  which directly or indirectly competes with the Company; or

                          (iv)    Otherwise enter into or engage in any business
                  which directly or indirectly competes with the business
                  carried on by the Company.

                  (b)     The Employee shall not at any time, either during the
     term of his employment with the Company or after the termination of such
     employment for whatever reason:

                          (i)     Disclose to anyone (except to the extent
                  necessary as a benefit to the Company in the performance of
                  his duties) any trade secrets or confidential information (as
                  defined below):

                          (ii)    Solicit any of the Company's employees to
                  leave the employ of the Company; or

                                      -5-

<PAGE>

                          (iii)   Seek to employ any of the Company's employees
                  (other than on behalf of the Company).

                  (c)     All inventions, discoveries, concepts, improvements,
     formulas, processes, devices, methods, innovations, designs, ideas, and
     product developments (collectively, the "Developments") developed or
     conceived by the Employee, solely or jointly with others, whether or not
     patentable or copyrightable, at any time during the term of his
     employment with the Company or within one year after the termination of
     such employment for any reason, whether or not during normal working
     hours, and which relate in any way to the actual or planned business
     activities of the Company shall be considered to be developed or
     conceived by the Employee on behalf of the Company within the scope of
     his employment, and all of the Employee's right, title, and interest
     therein shall be the exclusive property of the Company. The Employee
     hereby assigns, transfers, and conveys to the Company all of his right,
     title, and interest in and to any and all such Developments. Employee
     shall disclose fully, as soon as practicable and in writing, all
     Developments to the Board. At any time and from time to time, upon the
     request of the Company, the Employee shall execute and deliver to the
     Company any and all instruments, documents, and papers, give evidence,
     and do any and all other acts which, in the opinion of counsel for the
     Company, are or may be necessary or desirable to document such transfer
     or to enable the Company to file and prosecute applications for, and to
     acquire, maintain, and enforce, any and all patents, trademark
     registrations, or copyrights under United States or foreign law with
     respect to any such Developments or to obtain any validation, reissuance,
     continuance, or renewal of any such patent, trademark, or copyright. The
     Company will be responsible for the preparation of any such instruments,
     documents, and papers and for the prosecution of any such proceedings and
     will reimburse the Employee for all reasonable expenses the Employee
     incurs upon authorization of the Board.

                  (d)     The Employee understands that this section is an
     essential element of this agreement and that the Company would not have
     entered into this agreement without this section being included in it.
     The Employee has consulted with his legal counsel and has been fully
     advised concerning the reasonableness and propriety of this section in
     the specific context of the operations and business of the Company, and
     the Employee acknowledges that this section is reasonable and appropriate
     in all respects. In the event of any violation or attempted violation of
     this section, Employee specifically acknowledges and agrees that the
     Company's remedy at law will be inadequate, that the Company, its
     business, and business relationships will suffer irreparable injury and,
     therefore, that the Company shall be entitled to injunctive relief upon
     such breach in

                                      -6-

<PAGE>

     addition to any other remedy to which it may be entitled, either at law
     or in equity, without the necessity of proof of actual damage.

                  (e)     As used in this agreement, the terms "trade secrets"
     and "confidential information" shall mean any information which is not
     generally known to the public, and include without limitation any
     information relating to the Company's business operations and structure,
     sales methods, practices and techniques, technical know-how,
     Developments, advertising, marketing methods and practices, and the
     Company's relationships with suppliers, employees, or other persons or
     entities doing business with the Company.

                  (f)     For purposes of this agreement, "directly or
     indirectly" shall mean and include participation for the Employee's own
     account or as an owner, shareholder, member, partner, director, officer,
     employee, creditor, or agent of any other person or organization or
     through the Employee's spouse or other family relation, but shall not
     include a passive investment of not more than two percent of the
     outstanding stock of a company whose shares are then being regularly
     traded in open-market brokerage transactions (either on a stock exchange
     or over-the-counter).

                  (g)     In the event that a court of competent jurisdiction
     finally determines that any provision of this section is unenforceable,
     the Company and the Employee agree that such court shall have
     jurisdiction to reform this agreement and such provision so that it is
     enforceable to the maximum extent permitted by law, and the parties agree
     to abide by such court's determination.

     [sect]8.     General.  This document contains the entire agreement between
                  -------
the parties and supersedes any prior discussions, negotiations,
representations, or agreements between them relating to the employment of the
Employee. No additions or other changes to this agreement shall be made or be
binding on either party unless made in writing and signed by each party to this
agreement. Any notice or other communication required or desired to be given to
any party under this agreement shall be in writing and shall be deemed given
when either delivered personally to that party or deposited in the United
States mail, first-class postage prepaid, addressed to that party at the
address set forth below its or his name below. Any party may change the address
to which notices and other communications are to be given by giving the other
parties notice of such change. All questions concerning the validity,
intention, or meaning of this agreement or relating to the rights and
obligations of the parties with respect to performance hereunder shall be
construed and resolved under the laws of Ohio. If and to the extent that any
court of competent jurisdiction determines that it is impossible or violative
of any

                                      -7-

<PAGE>

legal prohibition to construe any provision of this agreement consistently with
any law, legal prohibition, or public policy and consequently holds that
provision to be invalid or prohibited, such holding shall in no way affect the
validity of the other provisions of this agreement, which shall remain in full
force and effect. No failure by any party to insist upon strict compliance with
any term of this agreement, to exercise any option, to enforce any right, or to
seek any remedy upon any default of any other party shall affect, or constitute
a waiver of, the first party's right to insist upon such strict compliance,
exercise that option, enforce that right, or seek that remedy with respect to
that default or any prior, contemporaneous, or subsequent default; nor shall
any custom or practice of the parties at variance with any provision of this
agreement affect, or constitute a waiver of, any party's right to demand strict
compliance with all provisions of this agreement. The captions of the various
sections of this agreement are not part of the context of this agreement, but
are only labels to assist in locating those sections, and shall be ignored in
construing this agreement. This agreement shall be personal to the Employee and
no rights or obligations of the Employee under this agreement may be assigned
by him.

                                         PINNACLE DATA SYSTEMS, INC.

__________________________________       By____________________________________
C. ROBERT HAHN                              John D. Bair, President and
                                            Chief Executive Officer

Address:     5765 Lee High Circle        Address:    6600 Port Road, Suite 100
             Nashport, OH 43830                      Groveport, OH 43125

                                      -8-