A method is described for preventing and comabating corrosion on semi-dry, moist and wet concrete marine structures, comprising that, against the surface of the structure to be protected on a permanent basis, there is fastened an inert, conductive material, pressed by the fastening against an intermediate contact-establishing, hydroscopic material, and where a voltage is applied on a permanent basis between the reinforcement in the concrete and the affixed inert, conductive material.