The photoelectrochemical properties of ap-type silicon (100) electrode coated with tungsten oxide thin film were investigated as a function of annealing temperature. The variation in the annealing temperature affected the photocurrent of aWO3/p-Sielectrode. A maximum photocurrent was obtained when the 500 ÅWO3thin film coatedp-Si electrode was annealed at 350 °C for 1 h. A further increase in the annealing temperature and film thickness degraded the photocurrent. This can be explained in terms of electrical resistivity, carrier concentration, and depletion layer width. AWO3thin film deposition on thep-Si shifted the flatband potential of thep-Si electrode by 0.3 V in the anodic direction, resulting in an improvement in conversion efficiency. These results are supported by x-ray diffraction, Auger electron spectroscopy, and capacitance measurements. ©1997 American Institute of Physics.