General demercaptanization of LPG sweetening method used in Iran's South Pars Gas Complex is a Sulfrex process that is based on the ability of a sulfonated cobalt phthalocyanine, to catalyze the oxidation of mercaptans to alkyl disulfides under caustic condition by air. The aims of this work were to study and optimize the caustic regeneration condition. At first caustic regeneration process was represented. Thereafter, effect of the main operating variables including regeneration temperatures, caustic concentration, and air injection rate to the oxidizer on the caustic regeneration were studied, and at the end operational process parameters according to laboratory results were optimized and tuned.