The effect of the support (graphite, activated carbon, silica and alumina) has been investigated using the conversion of n-hexane as model reaction. The catalysts were characterized by H-2 adsorption and transmission electron microscopy. Also, the CO adsorption was studied by microcalorimetry. The higher initial heat of CO adsorption observed on ruthenium/graphite indicates an enhanced electron density of the ruthenium particles caused by electron transfer from the graphite. The catalytic results show that ruthenium particles with an increased electron density have a higher activity for the n-hexane conversion accompanied by a preference for hydrogenolysis reaction, with the hydrogenolysis pattern corresponding to a multiple fragmentation. The higher resistance of ruthenium/graphite catalysts to deactivation by carbonaceous deposits was also observed.