The complex RhH(CO)(TPPTS)(3) [TPPTS = P(m-C6H4SO3Na)(3) = tris(sodium-m-trisulphonated-triphenylphosphine] was used as catalyst precursor for the hydroformylation of several C-6-C-7 alkenes from a real Venezuelan naphtha cut without dilution, under mild reaction conditions: 800 psi of syngas 1:1 (H-2/CO), substrate/catalyst molar ratio 400:1, 80 degrees C and 760 rpm. The olefin contents in the organic phase were about 42%. The catalytic precursor is active in the hydroformylation reaction of the naphtha cut obtaining conversion of 86% of the olefins in aldehydes during 200 h of reaction. The oxigenated products were nearly completely identified and agrupated according to the carbon atom number in order to facilitate our discussion. (C) 2009 Elsevier B.V. All rights reserved.