Pb(Zr0.52Ti0.48)O-3 (PZT) piezoelectric thin films with thickness of 0.7-2.2 mu m were prepared on Pt/Ti-coated SiO2/Si (0.5 mu m/300 mu m) substrates by the sol-gel method. The piezoelectric coefficient epsilon(31) of the PZT thin film was -12.5 +/- 0.3 c/m(2), which is evaluated by measuring the tip displacement of PZT-coated cantilevers of the dimensions 50 mm long, 4 mm wide, and 0.3 mm thick. The prepared PZT films demonstrated excellent piezoelectric properties and have large potential applications in MEMS devices. Micro-machined ultrasonic sensors, in which PZT-coated membrane functioned as sensing element, were fabricated and their properties were also characterized. (C) 2007 Published by Elsevier B.V.