Herein, the typical components of blast furnace gas, including H O and O , were introduced to improve the NH -SCR activity of the sulfated CeO -OS catalyst during the gas-phase sulfation of organic COS + CS at 50 °C. The characterization results demonstrate that the introduction of O or H O during gas-phase sulfation enhances the conversion of organic COS + CS on a cubic fluorite CeO surface and reduces the formation of sulfur and sulfates in the catalyst, but decreases the BET surface area and pore volume of the sulfated CeO -OS catalyst. However, the introduction of O or H O during the gas-phase sulfation increases the molar ratios of Ce /(Ce + Ce ) and O /(O + O + O ) on the sulfated CeO -OS catalyst surface, thus promoting the formation of surface oxygen vacancies and chemisorbed oxygen, and these properties of the catalyst are further enhanced by the co-existence of O and H O. Furthermore, the reduction of sulfates formed under the action of O or H O decreases the weak acid sites of the sulfated CeO -OS catalyst, but the few and highly dispersive sulfates present stronger reducibility, and the proportion of medium-strong acid sites of the catalyst increases. These factors help to improve the NH -SCR activity of the sulfated CeO -OS catalyst. Thus, there exists a synergistic effect of H O and O introduction during gas-phase sulfation on the physical-chemical properties and catalytic performance of the sulfated CeO -OS catalyst by organic COS + CS at 50 °C.