Pulverized Taiheiyo coal (Japanese subbituminous coal) was gasified with steam in the presence of CO 2 sorbent (Ca(OH) 2 ) under relatively high pressure (approximately 20 MPa; subcritical condition) using a tubing-bomb microreactor (TB reactor). The transient characteristics in the conversion of coal and the formation of gaseous products during the gasification were investigated. During initial heating period, 40-50 wt.% of the coal initially loaded was rapidly converted to gas or tar. In the presence of Ca(OH) 2 , the yield of gaseous products was apparently increased owing to the catalytic effects of Ca(OH) 2 on coal gasification. No CO 2 was observed in the produced gas at any soaking time in the gasification with Ca(OH) 2 , suggesting that CO 2 sorption by Ca(OH) 2 took place effectively under high-pressure conditions. A rigid agglomeration of char and CO 2 sorbent was observed at relatively high temperature, which is attributed to the formation of melts of the CO 2 sorbent.