A catalyst based on the ruthenium-trioctylamine complex supported on alumina was first used in selective hydrogenation of carbon dioxide to methane. The reaction was studied by the pulse method in a KL-2 apparatus at atmospheric pressure in a hydrogen flow. Optimum hydrogenation conditions were determined. The hydrogenation reaction proceeds in the kinetic region at all of the space velocities examined over the temperature range 400-500 K, but passes into the internal-diffusion region at temperatures higher than 500 K. Activation energies were calculated for the kinetic region. The activity of the metal complex catalyst was shown to be much higher than that of the catalyst obtained from the original salt. A possible mechanism of CO2 methanation is discussed.