A novel method for the preparation of water-soluble polypyrrole graft copolymers with polyamines or polyimines is described. The polyreaction is performed in acidic solution by using chemical oxidants, e. g. iron(III) chloride or ammonium peroxodisulfate. The graft copolymers showed electrical semiconductivity in the undoped state which can be placed between the high conductivity of polypyrrole and the nonconductivity of the polyimine. Their thermal stability at 250 degrees C is improved compared to polypyrrole. The novel graft copolymers are soluble in water over a wide pH range and have a good processability.