The petroleum heavy oils or residual oils are known to contain large amounts of sulfur, causing significant environmental concerns during the partial or complete combustion of these oils. The removal of sulfur species from such oil fractions is extremely difficult due to the recalcitrant nature of the sulfur species. The present work describes a novel process for sulfur removal from high boiling, high viscosity petroleum fractions, wherein a sulfur removal efficiency as high as 95% is observed. The process also sees a reduction in the asphaltene content of the treated oils by more than 50%. Further, the viscosity of the desulfurized oil was found to be significantly reduced by more than 90% as compared to that of the untreated or raw oil fraction. It is envisaged that utilization of this process for desulfurization of residual oils will result in much reduced SOx emissions, with accompanying environmental benefits.