Abstract: A method for desulfurizing a light sour oil by contacting the hydrocarbon fluid with a mesoporous catalyst at temperatures in the range of 20.degree.-500.degree. C. in the absence of molecular hydrogen to promote carbon--carbon and carbon-sulfur bond formation and increase the boiling point of sulfur containing hydrocarbons. The mesoporous catalyst is selected from the group consisting of alumina-silicate, alumina and silica, and is impregnated with an oxide of a metal that forms coordinate bonds with hydrocarbons in the hydrocarbon fluid. Suitable metals are aluminium, scandium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper and zinc. The hydrocarbon fluid may be contacted with the mesoporous catalyst in the presence of up to about 1 mole oxygen for each mole of sulfur in the sulfur containing hydrocarbons, or in the presence of an unsaturated hydrocarbon.