An acid-solubilized aqueous dispersion particularly suitable for use in the cathodic electrocoating art and stable up to pH of about 9 comprises the product of reacting substantially all of the epoxide groups of a polyether diepoxide with from about 1.25 to 2 moles of a polyamine having from 2 to 5 amine groups to form a precursor adduct and subsequently reacting this precursor adduct with about 0.2 to 2 moles of a mono-epoxide having a hydrolysis-resistant normal alkyl group of at least 4 carbon atoms to form a substantially epoxy-free polyamino polyhydroxy polyether resinous adduct, a sufficient proportion of the amine groups of said polyamine being primary or secondary to provide an amino hydrogen for reaction with every epoxide group of both the diepoxide and the mono-epoxide, and about 0.05 to 0.4 weight parts (per part of the resinous adduct) of an aminoplast resin having at least about one gram-equivalent of carboxylic acid groups with pK.sub.a from about 2 to 6 per 1,000 grams of aminoplast resin for catalyzing heat-induced curing of the resin mixture. The coatings cathodically electrodeposited from such dispersions exhibit superior corrosion and detergent resistance when cured at moderate temperatures.