<p>Herein, as typical solid acidic oxides, Tungsten was doped into the Ce_0.5Fe_0.5O_<i>x</i>-S catalyst to modulate its gas-phase sulfation by organic COS + CS₂, which enhanced the NH₃-SCR activity at low-medium temperatures, with an optimal doping molar ratio of W/(Ce + Fe) is 0.3. The characterization indicated that tungsten doping inhibited the adsorption and conversion of COS+CS₂ over the catalyst due to the enhanced interaction between iron and tungsten species. This effect diminished the diffraction peaks of iron sulfate and α-Fe₂O₃ at a W/(Ce + Fe) ratio of 0.5. The promoted Fe–W interaction also increased oxygen vacancies and enriched the pore structure. However, crystalline WO₃ formed at high doping levels shielded the Raman signals of cubic fluorite CeO₂ and surface oxygen vacancies, partially blocking pores and reducing the BET surface area. Interestingly, this promoted interaction increased the surface concentrations of both Ce³⁺ and Fe³⁺, and the Ce_0.5Fe_0.5W_0.3O_<i>x</i>-S catalyst even presented a larger surface concentration of Fe species than the Ce_0.5Fe_0.5O_<i>x</i>-S catalyst, although tungsten doping decreased the concentration of Ce species significantly. Furthermore, this promoted interaction reduced the amount of sulfates formed in the catalyst by restraining the gas-phase sulfation of Ce/Fe species, thereby regulating the total acid sites and weak acid sites/total acid sites proportion of Ce_0.5Fe_0.5O_<i>x</i>-S catalyst due to the different roles of the solid acidity of tungsten oxides and S⁶⁺ species in the formation of acid sites in W-doped Ce_0.5Fe_0.5O_<i>x</i>-S catalyst. It was found that both high levels of sulfate ions and tung-ten doping contributed to increasing the total acid sites of the catalyst.</p> Graphical Abstract <p></p>