Both a process and plant are provided for electrolytically coating with a metal layer the casting surface of a roll for twin-roll or single-roll continuous casting of thin metal strip. The casting surface is at least partially immersed in an electrolyte solution containing a salt of the metal to be deposited, so as to face at least one anode. The surface is placed at a cathode and a relative movement is created between the casting surface and the electrolyte solution. Insulating masks are interposed between the anode or anodes and the arrises of the casting surface, the insulating masks preventing a concentration of the lines of current on the arrises and in their vicinity.