Nonisothermal calcination and isothermal sulfation reactions of wasted oyster shell were conducted in the thermogravimetic analyzer in order to use as the sorbents for dry, high-temperature desulfurization system, The physical and chemical characteristics of sample were analyzed. Nonisothermal calcination reaction were conducted at the various heating rate under flowing nitrogen and CO₂gases. Sulfation reactions were conducted with respect to various factors:500-950℃ isothermal reaction temperature, 0.2-1% SO₂ concentration, and 0.7-5.0% O₂ concentration. Kissinger, Freeman-Carroll, Chatterjee-Conard and Achar method were used to analyze the calcination reactivity. The activation energy for the calcination reaction was 170.1 to 235.5 kJ/g-mol, and the reaction order for solid reactant was about 0.5 to 0.76. Measured activation energy for sulfation reaction was 24.4 kJ/g-mol in the temperature region from 550℃ to 650℃, whereas 31.5 kJ/g-mol in the range from 750℃ to 950℃. The reaction orders with respcet to SO₂ and O₂ concentration were 1.38 and 0, respectively. Maximum % conversion of the sulfaction reaction of the calcined oyster shell was shown to be over 80%.