Due to the future specifications for sulfur content in middle distillate like diesel, a lot of research work has been done to develop alternative methods for desulfurization. This work presents the results for the desulfurization of diesel by an oxidation and extraction (O/E) scheme. This process can be considered like a post-treatment to the traditional hydrodesulfurization. A diesel with 320 ppmw of total sulfur was employed to evaluate the elimination of sulfur compounds. The oxidation reaction was carried out with hydrogen peroxide at 30 wt.%, in a heterogeneous system with a WOx/ZrO2 catalyst at 15 wt.% of W; the extraction was performed with four polar solvents. The experiments were done in a batch reactor at 333 K and atmospheric pressure. As an average, the sulfur content in the diesel after treatment was 90 ppmw. A speciation of the sulfur compounds before and after O/E scheme was also included. Additionally, solubility data of dibenzothiophene sulfone in the polar solvents as a function of temperature were obtained. (C) 2004 Elsevier B.V. All rights reserved.