Ultrasonically assisted hydrothermal synthesis of PZT thin films was performed using an ultrasonic transducer integrated into the lid of an autoclave. Direct ultrasonic irradiation of 23 W at 53 kHz was carried out during the hydrothermal synthesis at a reaction temperature of 140 degrees C for 24 h. The resultant PZT thin film was characterized using scanning electron microscopy (SEM) and x-ray diffraction (XRD). The PZT thin film had fine nanoparticles of approximately 100 nm in diameter when the substrate was placed perpendicular to the plane of ultrasonic irradiation. The film exhibited predominantly (001) orientation when the substrate was placed parallel to the plane of ultrasonic irradiation.