Photocatalytic CO2 reduction was performed in a partially heterogeneous system using Ru and Co complexes: [Ru(bpy)(3)](2+) (bpy = 2,2'-bipyridine) as a photosensitizer was fixed to cation exchange polymers while [Co(bpy)(3)](2+) was used as a homogeneous catalyst. It was demonstrated that the metal complex system could be repeatedly used after replacement of the gaseous components by fresh CO2. Reuse of the complexes in the homogeneous systems was also experimented. As a result, increased CO production (TN = 8.3) was achieved in the heterogeneous system due to the prolonged catalytic activity more than 400 h under atmospheric pressure. Apparent deactivation of the system was discussed in terms of the intermediates of the Co complex. (C) 2002 Elsevier Science B.V. All rights reserved.