In order to develop an efficient absorbent for SO_2 in coal combustion, coal char-supported CaO was prepared from oyster shell in the presence Yallourn coal. Illinois No.6 coal was combusted by admixing the absorbent in a fixed bed reactor at 900℃. Performance of the absorbent was evaluated by the SO_2 concentration in the tail gas. In Illinois No.6 coal combustion without the absorbent about 710ppm of SO_2 was released. When the absorbent was mixed with Illinois No.6 coal (Ca/S=3), the SO_2 concentration in the tail gas decreased to 10ppm.