Hydrogenation of carbon monoxide and carbon dioxide (CO/H-2=CO2/H-2=1/3) on Raney ruthenium catalysts was carried out under pressures of 1.1 and 2.1 MPa using an autoclave in the presence of water at 353 and 433 K, Hydrocarbons, whose distribution followed the Schulz-Flory pattern, were produced from CO-H-2, together with a trace amount of methanol, The activities for their production have been much improved under high pressure, but the selectivity of methanol production decreased, probably due to the poisoning of active sites by water. The activity for methane production from CO2-H-2 at 433 K under 1.1 MPa was much higher than that under atmospheric pressure. The rate of methane synthesis was 3.0 mmol g(-1) h(-1) and the selectivity for methane formation was 98% at 353 K, suggesting the practical use of this catalyst. The activity and selectivity of CO and CO2 hydrogenation are discussed from mechanistic standpoints.