Catalytic hydrogenation of carbon dioxide over Ni/SiO₂ catalyst in a fixed-bed reactor was studied by varying the reaction temperature, space velocity, and mole fraction of the feed. Space velocity under 300 cm³/min·g-cat had no effect on the conversion of CO₂. Conversion of CO₂ increased and approached to the equilibrium conversion as the reaction temperature increased. There was no optimum fled composition for maximum COE conversion. Keeping the average feed composition in periodic operation with stoichiometric ratio of methanation reaction(H₂/CO₂=4), effect of cycle splits and periods of feeding cycle were studied. In periodic operation, conversion of CO₂ and selectivity of methane were lower than those of steady state runs. However, selectivity to CO increased by periodic operation. Cycle period resonance of CO₂ conversion was observed.