Hydroformylation of ethylene and CO hydrogenation were studied over cobalt-based catalysts derived from reaction of Co-2(CO)(8) with ZnO, MgO and La2O3 supports. At 433 K a similar activity sequence was reached for both reactions : Co/ZnO > Co/La2O3 > Co/MgO. This confirms the deep analogy between hydroformylation and CO hydrogenation into alcohols. In the CO hydrogenation the selectivity towards alcohol mixture (C-1-C-3) was found to be near 100% at 433 K for a conversion of 6% over the Co/ZnO catalyst; this catalyst showed oxo selectivity higher than 98% in the hydroformylation of ethylene. Magnetic experiments showed that no metallic cobalt particles were formed at 433 K. It is suggested that the active site for the step that is common to both reactions is related to the surface homonuclear Co2+/[Co(CO)(4)](-) ion-pairing species.