Exhibit 31.2
 CERTIFICATION
  1.
    
    I have reviewed this quarterly report on Form 10-Q of FuelCell Energy, 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 registrant as of, and for, the periods presented in
this report;4.
    
    The registrants other certifying officer 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 during the
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
accordance with 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 of the 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 quarter in the
case of an annual report)
that has materially
affected, or is
reasonably likely to
materially affect, the
registrants internal
control over financial
reporting; and
 5.
    
    The registrants other certifying officer 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 registrants board of directors (or persons performing the
equivalent function):
 (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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
registrants internal
control over financial
reporting.
 Date: June 8, 2010
    
    /s/ Joseph G. Mahler

Joseph G. MahlerSenior Vice President, Chief Financial Officer,Treasurer and Corporate Secretary(Principal Financial Officer and Principal Accounting Officer)