MGa2O4 (M = Zn, Ni) rods with similar crystallinity and BET surface area were prepared via a facile template-engaged reaction. The photocatalytic activities for water splitting of RuO2-loaded MGa2O4 (M = Zn, Ni) were investigated under high-pressure Hg lamp. RuO2-loaded ZnGa2O4 catalyst exhibited much higher photocatalytic activity than RuO2-loaded NiGa2O4. Factors affecting the photocatalytic activities of RuO2-loaded MGa2O4 (M = Zn, Ni) were discussed. It was suggested that the electronic structure of oxide semiconductor was a predominant factor of the photocatalytic behavior for RuO2-loaded MGa2O4 (M = Zn, Ni).