Photocatalytic hydrogen production was investigated over ZnS 1−x−0.5y O x (OH) y –ZnO using sulfide ion (Na 2 S–Na 2 SO 3 ) as an electron donor from NaCl saltwater. NaCl can affect markedly the activity for photocatalytic hydrogen production, depending on NaCl concentration. When NaCl concentration is lower, the activity is lower than that in pure water, whereas when NaCl concentration is higher, the activity is higher than that in pure water. NaCl decreases not only the surface charge of ZnS 1−x−0.5y O x (OH) y –ZnO but also the surface hydration. When ZnS 1−x−0.5y O x (OH) y –ZnO was impregnated with the electron donor (Na 2 S–Na 2 SO 3 ), ZnO was transformed partly into ZnS. The impregnated ZnS 1−x−0.5y O x (OH) y –ZnO exhibits higher activity than the non-impregnated one. The possible mechanisms were discussed.