Cellulose, a major component of woody biomass, reacts in hot-compressed water at 350 degreesC and 160-200 atm in the presence of a supported group 10 metal catalyst (2 wt%) for 10 min to give gas, consisting of hydrogen, carbon dioxide, and methane. Hydrogen was produced in high yield (8.1 mmol/g cellulose) and high selectivity (H-2/CH4 = Ca. 6) catalyzed by a supported Ni, Pd, or Pt. Among them, Pd supported on Al2O3 particularly had highest catalytic activity for this gasification.