EXHIBIT31.2

CERTIFICATION

I, Howard B. Johnson, ChiefFinancial Officer of Vion Pharmaceuticals, Inc., certify that:

1.    I have reviewed this annual report on Form 10-K of VionPharmaceuticals, Inc. (the "Registrant");

2.     Based on my knowledge, this annual report does not containany untrue statement of a material fact or omit to state a materialfact necessary to make the statements made, in light of thecircumstances under which such statements were made, not misleadingwith respect to the period covered by this annual report;

3.     Based on my knowledge, the financial statements, and otherfinancial information included in this annual report, fairly present inall material respects the financial condition, results of operationsand cash flows of the registrant as of, and for, the periods presentedin this annual report;

4.    The Registrant's othercertifying officer and I are responsible for establishing andmaintaining disclosure controls and procedures (as defined in ExchangeAct Rules 13a-15(e) and 15d-15(e)) for the Registrant and have:

a)    Designed such disclosure controls andprocedures, or caused such disclosure controls and procedures to bedesigned under our supervision, to ensure that material informationrelating to the Registrant, including its consolidated subsidiaries, ismade known to us by others within those entities, particularly duringthe period in which this annual report is being prepared;

b) Evaluated the effectiveness of theRegistrant's disclosure controls and procedures and presented inthis annual report our conclusions about the effectiveness of thedisclosure controls and procedures, as of the end of the period coveredby this annual report based on such evaluation;

c) Designed such internal control over financialreporting, or caused such internal control over financial reporting tobe designed under our supervision, to provide reasonable assuranceregarding the reliability of financial reporting and the preparation offinancial statements for external purposes in accordance with generallyaccepted accounting principles; and

d) Disclosedin this annual report any change in the Registrant's internalcontrol over financial reporting that occurred during theRegistrant's most recent fiscal quarter (the Registrant'sfourth fiscal quarter) that has materially affected, or is reasonablylikely to materially affect, the Registrant's internal controlover financial reporting;

5. The Registrant's othercertifying officer and I have disclosed, based on our most recentevaluation of internal control over financial reporting, to theRegistrant's auditors and the audit committee ofRegistrant's board of directors (or persons performing theequivalent functions):

a) All significantdeficiencies and material weaknesses in the design or operation ofinternal control over financial reporting which are reasonably likelyto adversely affect the Registrant's ability to record, process,summarize and report financial information; and

b) Any fraud, whether or not material, that involvesmanagement or other employees who have a significant role in theRegistrant's internal control over financial reporting.

Date: March 15, 2005

|  | /s/ HowardB. Johnson Howard B. Johnson Chief FinancialOfficer |
|--|---------------------------------------------------------------|

----