Photocatalysts for overall water splitting have great potential in solar energy applications. A variety of photocatalysts have shown activity for water splitting. In particular, oxysulfides are the great interest because of their ability to generate H2 and O2 from water under visible light. However, they are generally synthesized under H2S flow, which is an extremely harmful gas for humans. In this study, La2O2S2 was synthesized at low temperature without H2S gas, and its photocatalytic activity was confirmed by hydrogen generation experiments.