Recent development in titanium oxide-based photocatalysts was reviewed concerning the development in the highly dispersed titanium oxidephotocatalysts prepared on or within zeolites and the visible light-responsive TiO2 photocatalysts. The unique and high reactivities of titaniumoxide species anchored or incorporated in the zeolite for various photocatalytic reactions such as reduction of CO2 with H2O and directdecomposition of NOx into N2 and O2 were discussed focusing on the relationship between the reactivity and local structures of the catalysts.Moreover, the preparation of the visible light-responsive TiO2 photocatalysts by applying ion-engineering techniques such as an ion-implantationand an RF magnetron sputtering deposition method was discussed focusing on its unique reactivity for the decomposition of water into H2 and O2with a separate evolution under sunlight irradiation.