Commercial coke was modified by H₂SO₄ and (NH₄)²S₂O₈, respectively to enhance the adsorption and its catalytic activity. The properties of coke samples were characterized by BET, FTIR, SEM-EDX, XPS and in situ DRIFTS analysis.The activity performance was examined in a fixed bed reactor, and the effects of temperature, O₂, H₂O and CO₂ were investigated. The desulfurization performance of modified activated coke wasconsiderably enhanced by treatment with (NH₄)²S₂O₈. This is due to the existence of oxygen and nitrogen functional groups, and enhanced porous structure of modified activated coke. The DRIFTS behavior of SO₂ suggested that the presence of O₂ greatly promote SO₂ adsorptionand the modification by (NH₄)²S₂O₈significantly improves SO₂ oxidation and retention onactivated coke.