The hydrogenation of sunflower oil on TiO, supported by Pt catalysts was studied. The Pt/TiO2 catalyst was modified: (a) with K and (b) by high temperature reduction treatment, in order to observe its influence on the activity and the cis-isomers selectivity. The catalysts were characterized by atomic absorption, H-2 chemisorption, TPR and XRD. The hydrogenation of edible oils at conventional conditions is diffusion controlled. The addition of propane as supercritical (SC) solvent allows to perform the reaction in a homogeneous phase in contact with the solid catalyst. A significant increase in the reaction rate of the homogeneous system was observed. Regarding selectivity, the formation of trans-isomers was higher in the reaction under conventional conditions, whereas the production of saturated compound was favored in the homogeneous operation. Pt-K/TiO2 and Pt/TiO2 catalyst presented a similar TON, although the cis-isomer selectivity increased with the alkali addition. This behavior is explained in terms of a chemical modification of the noble metal. (C) 2007 Elsevier B.V. All rights reserved.