The catalytic activities of Rh and Ni metals supported on SiO2 or La2O3 were compared at CH4+CO2 reforming conditions and performing catalytic tests and thermal analyses in thermodynamic conditions favourable for carbon deposition. The deactivation of both the metals deeply depend on the support. An increased CO production is obtained with lanthana but the comparison between Rh and Ni on carbon deposition base suggests that a positive effect could be reached only at low methanation activity.