Preparation of 1,1,1,2-tetrafluoroethane from 1,1,1-trifluoro-2-chloroethane (HCFC-133a) by vapor-phase catalytic fluorination is described. The preparation of the catalyst, composed of transition metals on a gamma-AlF3 carrier, is reported, and the effect of reaction temperature, ratio of starting substrates and the contact time (CT) on the conversion and selectivity is investigated. Factors of catalyst deactivation are also discussed.