**Exhibit
      31.2**




**CERTIFICATION**




I,
      Jonathan R. Hunt, Chief Financial Officer, certify that:




1.  I
      have
      reviewed this quarterly report on Form 10-QSB of IsoRay, Inc.;




2.  Based
      on
      my knowledge, this report does not contain any untrue statement of a material
      fact or omit to state a material fact necessary to make the statements made,
      in
      light of the circumstances under which such statements were made, not misleading
      with respect to the period covered by this report;




3.  Based
      on
      my knowledge, the financial statements, and other financial information included
      in this report, fairly present in all material respects the financial condition,
      results of operations and cash flows of the small business issuer as of, and
      for, the periods presented in this report;




4.  The
      small
      business issuer's other certifying officer(s) and I are responsible for
      establishing and maintaining disclosure controls and procedures (as defined
      in
      Exchange Act Rules 13a-15(e) and 15d-15(e)) for the small business issuer and
      have:




(a)  Designed
      such disclosure controls and procedures, or caused such disclosure controls
      and
      procedures to be designed under our supervision, to ensure that material
      information relating to the small business issuer, including its consolidated
      subsidiaries, is made known to us by others within those entities, particularly
      during the period in which this report is being prepared;




(b)  Omitted;




(c)  Evaluated
      the effectiveness of the small business issuer's disclosure controls and
      procedures and presented in this report our conclusions about the effectiveness
      of the disclosure controls and procedures, as of the end of the period covered
      by this report based on such evaluation; and




(d)  Disclosed
      in this report any change in the small business issuer's internal control over
      financial reporting that occurred during the small business issuer's most recent
      fiscal quarter (the small business issuer's fourth fiscal quarter in the case
      of
      an annual report) that has materially affected, or is reasonably likely to
      materially affect, the small business issuer's internal control over financial
      reporting; and




5.  The
      small
      business issuer's other certifying officer(s) and I have disclosed, based on
      our
      most recent evaluation of internal control over financial reporting, to the
      small business issuer's auditors and the audit committee of the small business
      issuer's board of directors (or persons performing the equivalent
      functions):




(a)  All
      significant deficiencies and material weaknesses in the design or operation
      of
      internal control over financial reporting which are reasonably likely to
      adversely affect the small business issuer's ability to record, process,
      summarize and report financial information; and




(b)  Any
      fraud, whether or not material, that involves management or other employees
      who
      have a significant role in the small business issuer's internal control over
      financial reporting.









Date:
      May
      15, 2007





/s/
                Jonathan R. Hunt*Jonathan
                R. Hunt**Chief
                Financial Officer*








**
      The
      introductory portion of paragraph 4 of this certification that refers to the
      certifying officers' responsibility for establishing and maintaining internal
      control over financial reporting for the company, as well as paragraph 4(b),
      have been omitted in accordance with Release No. 33-8545 (March 2, 2002) because
      the compliance period has been extended for small business issuers until the
      first fiscal year ending on or after July 15, 2007.