Cathodic protection applied to reinforced concrete structures: experimental study and modelling. This article presents an experimental and numerical study of the impressed current cathodic protection applied on a reinforced concrete wall subjected to localized corrosion (macro-cell corrosion), typical of the reinforced concrete. The numerical study is carried out with COMSOL Multiphysics software. Experimental and numerical studies based on the basic physical laws that govern the electrochemical phenomena, confirm that the polarization of macro-cell corrosion systems is heterogeneous and can only be modelled in three dimensions. The uniformity of the potential field at the steel-concrete interface is physically not achievable by applying a protective current of the concrete surface. The general principle of cathodic protection does not have to be discussed, but special attention must be paid to the non-uniform response of macro-cell corrosion systems because it calls into question, among other things, the choice of the location of embedded probes where the performance of the PC system is evaluated and the use of criteria expressed in potentials.