Thermal analyses were conducted by isothermal technique in order to characterize the combus-tion and steam gasification reaction of coal chars that were carbonized from Dong-won anthracite, Australian Coalex(HD) bituminous coal, Australian Victoria subbituminous coal, and Pakistian Lakla lignite. Char combus-tion reactions were carried out with respect to various factors : char particle size(0.08-0.5mm), isothermal reaction temperature(560-680℃), oxygen concentration(5%-20%), and pyrolysis conditions. Char-steam gasifi-cation reactions were carried out at isothermal temperatures of 750-950℃. In combustion reaction, measured reaction orders of oxygen concentration and activation energy were 0.56-0.98 and 53-123kJ/g-mol, respectively. In char-steam gasification reaction, measured activation energy were in the range between 113kJ/g-mol and 165kJ/g-mol. The kinetic equation of char combustion and char-steam reaction was correlated with various factor.