The effects of the metal ion addition to SrTiO3 to the overall H2O splitting were investigated to improve the photocatalytic activity. The addition of metal ions was carried out by impregnation method. The preparation condition of metal ion added SrTiO3 was examined with applying Na+ ion as additive and SrTiO3 prepared by polymerizable complex method. The photocatalytic activity was markedly improved by the addition of Na+ ion and calcined above 1173 K. The preferable state of the photocatalyst was Na ion (2 atm%) added SrTiO3 obtained by calcination at 1273 K and the photocatalytic activity with a Rh0.3Cr1.7O3 (Rh:0.3 wt%) co-catalyst was 16 mmol/h for H-2 and 8 mmol/h for O-2 production. The apparent quantum yield (AQY) was 16% under the irradiation of 360 nm. The photocatalytic performance of Na+ ion added various SrTiO3 and the effects of various metal ion addition to SrTiO3 to the photocatalytic activity of the overall H2O splitting were investigated to discuss the influence of the added metal ions to the photocatalytic activity. (C) 2015 Elsevier B.V. All rights reserved.