A method of extraction of low molecular weight mercaptans from petroleum (e.g., crude oil) or gas condensate containing such mercaptans comprises (1) contacting the mercaptans with oxygen in an aqueous solution of a metal hydroxyde, in the presence of a cobalt dihalodihydroxydisulfophthalocyanine catalyst, the catalyst being used in an amount within the range of from about 0.5 x 10-5 to about 2.5 x 10-5 weight percent based on the weight of the petroleum or gas condensate, the catalyst being introduced into the crude oil or gas condensate continuously in the form of a catalytic complex in an aqueous solution of a metal hydroxide, the extraction method being conducted at a temperature ranging from about 40 to about 60 °C and a pressure ranging from about 1.0 to about 1.4 MPa, and (2) separating the petroleum or gas condensate fro m the aqueous solution of metal hydroxyde.