Hydrogenation of ol,P-unsaturated alcohol, nitrile, aldehyde, ketone, carboxylic acid and amide catalyzed by a novel water-soluble complex [Rh-4(O2CPrn)(4)Cl-4(CH3CN)(4)] was investigated. The reactions were carried our in aqueous solution at room temperature under 1 atm of H-2. The results showed that this tetrarhodium(II) complex is efficient for the hydrogenation of both terminal and internal double bond with the selectivity of unhydrogenated carbonyl groups. Unsaturated ketone, amide and carboxylic acid were readily hydrogenated, and nitrile and aldehyde were slowly hydrogenated. The hydrogenation of allyl alcohol was accompanied with isomerization to propanal. The rate of the hydrogenation was first-order to the catalyst precursor.