The atmospheric hydroformylations of ethylene and propylene were investigated over SiO2-supported Rh4(CO)12, Co2(CO)8, Rh2Co2(CO)12 and RhCo3(CO)12-derived catalysts. The bimetal cluster-derived catalysts showed excellent activities for the formation of oxygenates. In situ IR study on partially dehydroxylated SiO2-supported RhCO3(CO)12 suggested that the bimetal cluster framework may be preserved after decarbonylation under H-2 at 623 K and may be recarbonylated at room temperature. A strong physisorption of RhCo3 (CO) 12 on SiO2 is proposed, due to a nucleophilic attack of surface oxygen on the Co atoms, which promotes a metal-support interaction and thus stabilizes the bimetal cluster framework. A subcarbonyl bimetal cluster is thought to be the actual catalytic species on the surface.