A method of improving or “sweetening” the odor of gasoline, petroleum solvents, or kerosene. A doctor solution of sodium plumbite, Na2PbO2, is made by dissolving litharge in sodium hydroxide solution; the feed to be sweetened is passed through the doctor solution. The action of the sodium plumbite and the lead sulfide formed from it, in conjunction with free sulfur(either naturally present or added), converts the malodorous mercaptans to the pleasanter disulfides.