A desulfurization process for light oils has been investigated, based on the formation and subsequent adsorption of N-tosylsulfimides, produced by the reaction of the sulfur compounds in the light oils, with chloramine T (sodium N-chloro-p-toluenesulfonamide). Dibenzothiophenes (DBTs) in light oils are converted, by the reaction with chloramine T dissolved in methanol, to form the corresponding sulfimides and are removed into the methanol under moderate conditions, whereas benzothiophenes (BTs) gave rise to the corresponding chlorine-adduct products, on their unsaturated bond. The sulfimides of alkyl-substituted DBTs, formed during the reaction, remained in the resulting light oil, such that the deep desulfurization (0.05 wt %) failed to achieve. These compounds however were removed successfully by the addition of aluminum oxide adsorbent and the sulfur concentration of the light oil was decreased to less than 0.05 wt %. The desulfurization of high-aromatic-content light oil is relatively more difficult, because the aromatic hydrocarbons are chlorinated by reaction with chloramine T, proceeding competitively with chlorination of the sulfur compounds.