Pb(Sc 0.5 Ta 0.3 )O 3 (PST) thin films have been prepared by a Sol-Gel method to investigate the synthesis of the perovskite phase at low temperature. The effects of the composition of PST (amount of Pb excess) and the firing conditions (especially rapid thermal firing) have been studied. As a result of the experiments, it was found that rapid heating is effective for the synthesis of the perovskite phase and it is possible to deposit films at about 520°C. The Pb content of the sol does not have a marked effect upon the perovskite phase formation temperature. but it effectively depresses the formation of the intermediate pyrochlore phase.