  The recent detection of a hard X-ray component in the supernova remnant
Cassiopeia A is interpreted as synchrotron emission from electrons accelerated
to energies up to 40 TeV (Allen et al., 1997). It is therefore tempting to
consider TeV gamma-ray emission from this object through : i) bremsstrahlung
and inverse Compton radiation from electrons and/or ii) pi0 production from an
associated high energy cosmic ray component hitting surrounding material. Cas A
was observed by the CAT imaging Cherenkov telescope during the observing season
Aug-Nov 1998. An upper limit to the integral flux above 400 GeV of 0.74x10^-11
gamma.cm^-2.s^-1 is derived. This result is used to constrain
shock-acceleration models for production of VHE gamma-rays in SNRs.
