The crystallisation kinetics of amorphous sol-gel PZT thin films were investigated using high-temperature X-my diffraction. Crystallisation for different isotherms was monitored as a function of time. Phase transformation data were obtained from integrated X-ray peak intensities which were calibrated based on image analysis of the surface microstructure of the samples at the end of the isothermal treatments. An activation energy of 310 kJ/mol was obtained without assuming a specific kinetic model. Front the transformation data, a TTT diagram was constructed for the ranges studied. (C) 1997 Elsevier Science Limited.