Colloidal Pd, Ru and Pd-Cu areprepared in polyol solution (pi-opane-1,2-diol) by eithersteric stabilization via poly(N-vinyl-2-pyrrolidone) (PVP) or electrostatic stabilization. The coordination capture is carried out with gamma-mercaptopropyltriethoxysilane (gamma-MPS) and 3-aminopropyltriethoxysilane (3-APS) previously grafted on the Nb2O5 and Al2O3 supports via the silane group. After interaction of the colloidal solutions with the grafted support, the immobilization yield is nearly 100% in the case of electrostatic stabilization but lower for steric stabilization. All catalysts present it very good global selectivity in the liquid-phase hydrogenation of hexa-1,5-diene (selectivity to hexenes). The PVP-protected samples present an initial induction time (30-50 min) due to the partial elimination of PVP by the solvent n-heptane). The activity and hex-1-ene productivity of immobilized Pd samples are higher than those of unsupported colloidal Pd and immobilized Ru. This promising method, which avoids direct metal-support interactions, offer new possibilities to control the shape, size and structure of metal nanosized particles in a colloidal form, without change upon heterogenation. (C) 2002 Elsevier Science B.V. All rights reserved.