We prepared two types of SrTiO3-based photocatalyst powders, Bi,Ga-doped SrTiO3 and In,V-doped SrTiO3. UV-visible reflectance spectra of these powders indicated that their band-gaps remained constant in comparison with that of SrTiO3. In conjunction with the reported band structure control of oxides, our results indicated that Bi,Ga-doped SrTiO3 and In,V-doped SrTiO3 formed isolated mini-bands composed of Bi 6s orbitals in the forbidden band above the valence band, composed of O 2p, and V 3d orbitals below the conduction band, composed of Ti 3d, resulting in the observed visible-light absorption. Utilizing the prepared SrTiO3-based photocatalysts, we established a two-step overall water-splitting system, in which simultaneous liberation of hydrogen and oxygen with a molar ratio of similar to 2:1 was observed in the presence of I- (NaI) under irradiation with UV-containing light. Moreover, visible light contributed the cycling of 1(-)/IO3- redox mediators, resulting in enhanced hydrogen and oxygen liberation when compared to irradiation with UV light alone. (C) 2012 Elsevier B.V. All rights reserved.