The present invention relates to novel compositions uniquely comprising combinations of different grades and/or type of epoxy resins and phosphoric acid into stable, water dispersion, epoxy phosphate ester copolymers. Aqueous thermosetting coating compositions, based on the novel epoxy phosphate ester resins, have the ability to reduce the requirements of curing temperature and time. The resultant coating films have superior protective properties, film properties, and wider applications than the conventional epoxy phosphate ester resins.