The photocatalytic reaction of water was studied on a cerium oxide photocatalysts system. Cerium oxide photocatalyst showed a high evolution rate of hydrogen with cesium loading. In comparison to the adsorption properties, the adsorption strength of oxygen was superior to that of hydrogen. The variation of product distribution during the water photolysis reaction was mainly influenced by the adsorption properties of hydrogen and oxygen. Metal carbonate additives to the water photolysis reaction accelerated hydrogen evolution by photodecomposition of themselves.