Recently, polyoxometalates (POMs) have been widely investigated as a homogeneous photocatalyst and their photocatalytic activity has been successfully demonstrated. The photocatalytic oxidation capability of POMs is comparable to that of the heterogeneous TiO₂ photocatalyst. Like TiO₂, POMs are inactive under visible light irradiation. However, the dye-sensitization process was recently demonstrated for the dye/POM system as the dye degradation in visible light-illuminated TiO₂ is enabled through the sensitization mechanism. In this respect, we may expect that the photosensitized degradation of dye is enhanced with POM/TiO₂ composite compared with TiO₂ alone. In this study, POM/TiO₂ composite catalysts were synthesized using titanium-butoxide via sol-gel method. The physicochemical properties of these catalysts were investigated. The original Keggin structure of POM was retained in the POM/TiO₂ catalysts. SiW12/TiO₂ calcined at 350oC has higher photocatalytic activity than PW12/TiO₂ and PMo12/TiO₂ for the degradation of Rhodamine B (RhB) under visible irradiation. Acid Orange 7 (AO7), an anionic dye, was not degraded by POM/TiO2 under visible irradiation since the surface charge of POM/TiO₂ catalysts is predominantly negative and the electrostatic repulsion hinders the sensitization process. The effects of various experimental parameters were investigated and discussed.