This work mainly involved the investigation of the adsorption of propylmercaptan (PM) on modified bentonite adsorbents. The adsorbents were prepared by loading it separately with Cu2+, Cu+, Fe3+, and MnO4-. In general, these bentonite adsorbents tested for sulfur adsorption capacity at breakthrough followed the order: KMnO4-bentonite > Cu(I)-bentonite > Cu(II)-bentonite > Fe(III)-bentonite. Several factors that influence the desulfurization capability, including loading and baking temperature, were investigated. The results of X-ray diffraction (XRD), nitrogen sorption (BET), thermal analysis (TGA), and Fourier transform infrared (FT-IR) spectroscopy showed that the ability of modified bentonite to adsorb PM depends strongly on its surface chemistry, particularly on the presence of basic oxygen-containing groups and acid content. The high sulfur capacities of KMnO4-bentonite and Fe(III)-bentonite were because of the powerful oxidization of MnO4-and Fe3+. The high sulfur capacities of Cu(I)-bentonite and Cu(II)-bentonite were due to pi-complexation.