Heterogeneous reaction of carbonyl sulfide (OCS) on the surface of different types of alumina (Al2O3) at 298 K was investigated in a closed system and a flowed system using in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). The effects of calcination temperature of the Al2O3 on its catalyzed reactivity were studied. The crystal structure and surface area of the Al2O3 were characterized using X-ray diffraction (XRD) and the Brunauer-Emmett-Teller (BET) method. This paper revealed that adsorbed OCS could be catalytically oxidized on the surface of Al2O3 to form gas-phase CO2 and surface hydrogen carbonate (HCO3-) and sulfate (SO42-) species at 298 K. The surface hydroxyl (OH) species on the Al2O3 had been found to be the key reactant for the heterogeneous oxidation of OCS. Furthermore, the surface hydrogen thiocarbonate (HSCO2-) species, an intermediate formed in the reaction of OCS with OH, can be observed on the thermal-treated Al2O3. On the basis of these results, the reaction mechanism of heterogeneous oxidation of OCS on Al2O3 is discussed.