The hydrosoluble complex [Rh(mu-Pz)(CO)(TPPMS)](2), Pz=pyrazolate ligand, and TPPMS=(C6H5)(2)P(C6H4SO3Na) was used as catalytic precursor in the two phase hydrogenation reaction of the individual olefins (1-hexene, styrene, cyclohexene and 2,3-dirnethyl-1-butene) to give the main expected saturated products. Under the best operational conditions (80 degrees C, 200 psi H-2, S/C 535/1, and 600 rpm), the substrates showed the following hydrogenation reactivity order: 1-hexene > styrene > cyclohexene > 2,3-dimethyl-l-butene. The quaternary equimolar mixture of olefin and an olefin mixture that simulates a real composition of olefin present in a naphtha showed a different hydrogenation order; styrene > 1-hexene > cyclohexene > 2,3-dimethyl-1-butene. The catalyst can be recycled without significant loss of activity and showed sulfur tolerance, demonstrated by using benzothiophene in the olefin mixtures. (c) 2007 Elsevier B. All rights reserved.