The coal energy is presently one of the most promising alternative energy resources, and R & D activities on its gasification are reviewed to provide a stimulant for similar efforts in energy importing Korea. This review of available fundamental information focuses on analyzing the mechanism of the complex chemical and physical phenomena of the various primary gasification processes-thermal decomposition, direct and indirect hydrogasification, and catalytic gasification-and of the down stream processing including water gas shift conversion and methanation. The state of the art for typical gasifiers-moving bed, fluidized bed, entrained bed, and molten bath-is also extensively reviewed.