**Exhibit 31.1**

**CERTIFICATION**

I, Surendra Pai,certify that:

1.      I    have reviewed this Quarterly Report on Form 10-Q of Authentidate HoldingCorp.;

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, notmisleading 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 registrant as of,and for, the periods presented in this report;

4.      The    registrant’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)) and internal control over financial reporting    (as defined in Exchange Act Rules 13a-15(f)and 15d-15(f)) for the registrant 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 registrant, including its consolidated subsidiaries,    is made known to us by others within those entities, particularly duringthe period in which this report is being prepared;

b)      Designed    such internal control over financial reporting, or caused such internal control    over financial reporting to be designed under our supervision, to provide    reasonable assurance regarding the reliability of financial reporting and    the preparation of financial statements for external purposes in accordancewith generally accepted accounting principles;

c)      Evaluated the effectiveness of the registrant’s    disclosure controls and procedures and presented in this report our conclusions    about the effectiveness of the disclosure controls and procedures, as ofthe end of the period covered by this report based on such evaluation; and

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

5.      The registrant’s other certifying officer(s) and I have disclosed, based on our most recent evaluation of internal control over financial reporting, to the registrant’s auditors and the audit committee of the registrant’sboard 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 registrant’sability 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 registrant’sinternal control over financial reporting.

               
Date: November    9, 2005Name: /s/Surendra    Pai    Title:Chief Executive Officer