A method for maintenance of used permanent cathode plates, said used cathode plate having scratches, crud formations and oversize grain boundaries on a surface of the cathode plate. The method comprises removing of scratches and accumulated crud from the surface of the cathode plate. The method further comprises removing substantially completely the oversize grain boundaries from the surface, and thereafter regenerating the grain boundaries of the surface of the cathode plate to an average grain boundary width of 1 to 3 μm and an average grain boundary depth less than 1 μm.