An artificial photocatalytic system mimicking photosystem I (PSI) has been assembled using semiconductor (CdS) as photosensitizer, cobaloximes (Co III complexes) as H 2 evolution catalysts, and triethanolamine (TEOA) as sacrificial electron donor. This artificial photocatalytic system shows high hydrogen evolution activity (turnover number up to 171 based on Co III(dmgH) 2pyCl 1) under visible light irradiation. The apparent quantum efficiency (QE) for 1/CdS hybrid photocatalytic system in acetonitrile solution at 420 nm is calculated to be 9.1%. The interfacial electron transfer from photoexcited CdS to Co III complexes is very efficient through the weak adsorption of Co III complexes on CdS. The adsorption of 1 on CdS in acetonitrile fits Langmuir equation, the maximum monolayer adsorption capacity is 3 × 10 −3 mmol g −1, which means most of 1 are in the solution. The rate of hydrogen production exhibits a quadratic dependence on the total concentration of 1. Therefore, a bimetallic catalysis pathway is proposed. The efficient electron transfer, the broad electronic absorption character of CdS photosensitizer as well as the H 2 evolution ability of Co III complexes, account for the high photocatalytic activity of this hybrid photocatalytic system.