Pyrolysis and gasification of lignocellulosic (woody) biomass and its main components, cellulose, xylan, and lignin, were studied using a combined thermogravimetry and gas chromatography experimental setup at a heating rate of 10 degrees C min(-1) in the temperature range of 140-900 degrees C using air and/or steam gasifying agents (100% air, 50% air/50% steam, 25% air/75% steam, and 70% steam/30% argon). Simulated biomass composed of a mixture of cellulose, xylan, and lignin at 50:25:25 wt % was also investigated. A three-parallel-reaction kinetic model was formulated on the basis of the weighted sum of reaction rates for the individual components and experimentally validated in terms of reaction rates, carbon conversions, and product gas yields for lignocellulosic and simulated biomass.