Photocatalytic activity of BiVO4 for the water oxidation was found extensively improved by Mo doping. The highest activity of Mo doped BiVO4 for O-2 evolution appeared when the photocatalysts was doped by 0.2 at % Mo. The XRD patterens showed that the crystal structure of the photocatalyst was changed by Mo doping. The color and UV-Vis absorption spectra of the photocatalysts were also changed before and after the catalysts were doped by Mo.