In this study, undoped ZrO2 thin films were deposited on single-crystal silicon substrates using liquid phase deposition. The undoped films were formed by hydrolysis of zirconium sulfate (Zr(SO4)(2)center dot 4H(2)O) in the presence of H2O. A continuous oxide film was obtained by controlling adequate (NH4)(2)S2O8 concentration. The deposited films were characterized by SEM, FT-IR, XRD and DTA. Typically, the films showed excellent adhesion to the substrate with uniform particle diameter about 150 nm. The thicknesses of ZrO2 film were about 200 nm after 10 h deposition at 30 degrees C. These films shows single tetragonal phase after heat treated at 600 degrees C. High annealing temperature (e.g. 750 degrees C) may result in the phase transformation of (t)-ZrO2 into (m)-ZrO2. (c) 2006 Elsevier B.V. All rights reserved.