This work explores a novel approach to desulfurization of whole crude oil where thiophenic sulfur compounds are oxidized to sulfones followed by sulfone decomposition into sulfur-free hydrocarbons. The objective of this work is to study the effect of alkaline earth metal oxides on decomposition of sulfones in oxidized crude oil. About 73% of the sulfones in a preoxidized, medium sour crude oil was decomposed over CaO at 360 degrees C.SO2 was detected by TPD-MS and also measured by a quantitative method when the spent CaO sorbent was thermally treated in an inert atmosphere with sweep gas. No prominent decomposition of sulfur compounds was observed when untreated crude oil (not oxidized) was treated over CaO at 360 degrees C. This study demonstrates the feasibility of decomposing sulfones in oxidized crude oil over CaO-based materials.