Water-dispersible thermosetting coating composition

An aqueous thermosetting coating composition suitable for electrodeposition onto the surface of an article used as a cathode and comprising an aqueous solution or dispersion of a resinous material and an organic and/or inorganic acid, said resinous material being prepared by reacting (i) a secondary amine with (ii) epoxy groups pendant from a main chain of a copolymer of 5-50% by weight of an ethylenically unsaturated monomer containing epoxy groups and 50-95% by weight of one or more of vinyl or acrylic unsaturated monomers which do not contain epoxy groups and which are copolymerizable with the ethylenically unsaturated monomer, wherein said vinyl or acrylic unsaturated monomers are selected from the group consisting of styrene, substituted styrenes, vinyl esters of alkanoic acids containing 2-18 carbon atoms, acrylonitrile, methacrylonitrile, 1-18 carbon atoms-containing alkyl esters of acrylic or methacrylic acid, 2-4 carbon atoms-containing hydroxy alkyl esters of acrylic or methacrylic acid, and dialkyl esters of .alpha.,.beta.-unsaturated dibasic acids, the amount of the secondary amine being 0.1-0.8 equivalent per 1 equivalent of epoxy groups contained in said copolymer.