Tungstic acid (H2WO4) was first revealed to function as a stable and efficient photocatalyst for water oxidation in the presence of Fe3+ as an electron acceptor by utilizing a wider range of visible light compared to the conventional WO3 photocatalyst. Simultaneous evolution of H-2 and O-2 was demonstrated by combining the H2WO4 photocatalyst with an appropriate H-2-evolving photocatalyst in the presence of Fe3+/Fe2+ electron mediator.