Waste tires are one potential source of alternative energy because of their long chain hydrocarbon with a high calorific heating value. However, the pyrolysis oil that is derived from waste tires is not appropriate for direct use in a combustion process due to its high sulfur content. Therefore, the oxidative desulfurization (ODS) process was evaluated for its ability to reduce the sulfur content of the naphtha fraction distillated from light oil derived from waste tire pyrolysis. The addition of formic acid to pH of 4.0 in the presence of 25 vol.% hydrogen peroxide (H2O2) and tire pyrolysis char enhanced the level of sulfur removal to ca. 70% due to the simultaneous adsorption and oxidation of sulfurous compounds on the surface of the pyrolysis char. The chemical treatment to form surface-modified char promoted the benefit for ODS process in the presence of formic acid (pH 4) and H2O2 (25 vol.%) by increasing the sulfur reduction in the pyrolysis naphtha up to 75%. (C) 2010 Elsevier Ltd. All rights reserved.