Coal/CaO powder mixtures were continuously supplied into a reactor to react with steam at high pressure and high temperature. At 923 K and 5.0 MPa, the gas produced from the reaction of Taiheiyo coal/CaO with steam consisted of mainly H-2, with smaller amounts of CH4, C2H4, C2H6 and CO2. Increasing the pressure enhanced H-2 production and CH4 decomposition. Above 3 MPa, the gas from the reaction contained <3% CO and CO, Under high pressure, CaO reacted with steam to form Ca(OH)(2) which absorbed CO2. The H-2/CH4 ratio in the product gases from three different rank coals Datong coal (bituminous), Taiheiyo coal (sub-bituminous), Wyoming coal (lignite) followed the order Datong > Taiheiyo > Wyoming. The Wyoming and Datong coals produced less H-2 than the Taiheiyo coal. (C) 2003 Elsevier Ltd. All rights reserved.