Immobilization of small and homogeneously dispersed ruthenium nanoparticles stabilized by 4-(3-phenylpropyl)pyridine ligand (RuL) on functionalized multi-walled carbon nanotubes (RuL-MWCNT) have been prepared and characterized by elemental analysis and transmission electronic microscopy. A comparative hydrogenation study of unsaturated substrates using non-supported (RuL) and supported catalytic systems (RuL-MWCNT) was carried out. For all the substrates, the activity of the supported catalyst was higher towards the full hydrogenated product than that obtained using the non-supported one. Moreover, the catalytic effect of the support nature was studied using RuL immobilized on silica (RuL-SiO2), alumina (RuL-Al2O3) and activated carbon (RuL-AC). The best activities and selectivities were found for RuL-MWCNT system, maintaining its catalytic behaviour upon recycling. (C) 2010 Elsevier B.V. All rights reserved.