Abstract: Two kinds of immobilized Ru catalysts were synthesized by anchoring different ruthenium complexes on the functionalized mesoporous MCM-41 and then characterized with elemental analysis, atomic absorption spectrophotometer, UVVis and FT-IR. Hydrogenation of carbon dioxide to formate was investigated over these catalysts in CO2expanded solvent. The effects of solvents and bases on the catalyst activity were also examined. These two catalysts are different in their activities and stabilities, especially at lower temperature and hydrogen partial pressure. High formate yield is obtained and no byproduct is detected. The immobilized Ru catalysts are promising in industry due to the facility in catalyst separation and reuse.