The optimal working temperature in which the CO conversion is maximum and the CO2 conversion is minimized was determined to be from 149°C to 239°C for S-RuAl and from 165°C to 232 °C for M-RuAl, whilst it was from 217°C to 226°C for RuAl powder. TPR, XRD and TEM measurements confirmed that the changes in the activity and selectivity for CO methanation among the considered catalysts can be related with modifications in the surface particle size of ruthenium and its reducibility. These were ascribed to the metallic substrate, the presence of PVA and colloidal alumina in the slurry preparation, the aqueous and acidic media and the thermal treatment used, resulting in a more active and selective catalysts than the parent powder.Key words: RuO2/Al2O3; fecralloy micromonolith; CO and CO2 methanation