A method for reducing mercaptan concentration in a liquid hydrocarbon, comprising: contacting a mercaptan-rich liquid hydrocarbon having a first concentration of mercaptan sulfur with a composition comprising an oxidizing agent and water wherein the molar ratio of the oxidizing agent to mercaptan sulfur in the mercaptan-rich liquid hydrocarbon is from 3:1 to 10:1; and separating the water from the liquid hydrocarbon to yield a mercaptan-depleted liquid hydrocarbon having a second concentration of mercaptan sulfur, the second concentration being less than the first concentration; wherein a major amount of mercaptan compounds in the mercaptan-rich liquid hydrocarbon are converted to at least one sulfur oxoacid or salt thereof, having the formula: [RSOx]nY wherein R is a hydrocarbyl group; x is an integer from 1 to 3; n is 1 or 2; and Y is hydrogen, an alkaline metal, or alkaline earth metal.