This paper reports the study on the effect of addition of various amounts of Ru to supported Ni catalysts towards the CO2 reforming of methane. Catalytic activity results have shown that in the case of silica supported samples addition of Ru strongly enhances the catalytic performance of the Ni sample, both in terms of activity and stability. The influence of Ru addition is instead much less remarkable on H-ZSM5 zeolite supported samples. On the basis of FT-IR spectra of adsorbed CO, H-2 and O-2 chemisorption and temperature-programmed reduction measurements, it has been proposed that the different trend observed on the two series of catalysts is related to different metal-metal and metal-support interactions occurring on the catalysts. In particular, the strong improvement in the activity and stability observed on silica supported Ni-Ru bimetallic samples has been attributed to an increase in the metallic dispersion of Ni as a consequence of the formation of Ni-Ru clusters with the surface mainly covered by Ni.