The chemical reactivity and kinetics of nine Canadian coal samples ranking from lignite to semianthracilte and one wood sample were examined in a fixed gasifier in the presence of air and steam at 950-1000℃. The reactivity of the coal and wood samples decrease with an increase in carbon content, but increase with increasing oxygen content of the parent coal. The reaction mechanism based on the shrinking core model for the present gasification has been found to be chemical reaction controlled for the coal-steam-air system and ash-layer diffusion controlled for the wood-steam-air system. The present reaction system favors the water gas shift reaction based on the chemical composition of the product gas from the gasification.