Much SO₂, another perilous air pollutant, was emitted during the oxidative regeneration of sulfided sorbent by H₂S. In order to prevent emission of SO₂, we carried out oxidative regeneration with the physical mixture of CaO and sulfided sorbent and investigated the effect of regeneration temperature and oxygen concentration on the reactivity of CaO with SO₂. The effluent gases were analyzed by G.C. and the properties of sorbent were characterized by XRD, SEM, TG/DTA and EPMA. Deterioration of reactivity of CaO with SO₂ resulted in increment of emission of SO₂ due to the structural changes of CaO above 750℃ and that at 850℃ was more severe. Furthermore EPMA and XRD analysis revealed that product layer diffusion through the solid product, CaSO₄, was the rate limiting step for CaO sulfidation. The reaction of CaO with SO₂ was first order approximately and that was accelerated by high O₂ concentration.