K0.5Na0.5NbO3 thin films were prepared on Pt/Ti/SiO2/Si substrates by chemical solution deposition method with different annealing temperatures of 550 degrees C, 600 degrees C, 700 degrees C. The post-annealing treatment was introduced at 550 degrees C for 3 min in oxygen ambient. It is found that the films were composed of pure provskite phase, and the post-annealing treatment promoted the crystallization and improved the quality of the films, which resulted in the enhancement of the dielectric property of the films. The effect of the post-annealing on the dielectric properties of the films was also discussed. (C) 2011 Elsevier B.V. All rights reserved.