Transmission electron microscopy (TEM) was used to investigate the microstructural evolution of sol-gel derived ferroelectric PZT films. Aggregates of perovskite crystals nucleated and grew out of a pyrochlore matrix at 550°C. A dense, single-phase perovskite PZT film was obtained by fast firing the film at 650°C for 30 minutes. The grain size of this film was approximately 0.2-0.4 μm. Hot-stage TEM observed disappearance of ferroelectric domains as the temperature approaching 325°C.