Abstract: CaTiO₃ powder was synthesized by solid-state reaction of calcium nitrate with TiO(OH)₂ formed by hydrolysis of tetrabutyl titanate.The effect of supported promoters on the photocatalytic activity of CaTiO₃ for the decomposition of water to hydrogen was studied, and the results showed that the photocatalytic activity of CaTiO₃ could be promoted by CoO, NiO and Ag, and that the effect of CoO was the best.The influence of the treatment method for the supported samples on photocatalytic activity of CaTiO₃ was investigated and the samples were characterized by means of XRD, XPS and SEM.The results showed that the structure of Co-covering CoO distributing uniformly over the surface of CaTiO₃ was obtained after Co(NO₃)₂-impregnated CaTiO₃ sample underwent thermal decomposition, reduction by hydrogen at 500 ℃,and then oxidation by oxygen at 200 ℃, and the catalyst with this structure showed higher activity.The photocatalysis mechanism of CoO/CaTiO₃ was discussed.