[en] The electrochemical behaviour of AISI 304 and 304L stainless steels implanted with N⁺ or Ne⁺ ions in 0.5 and 0.02 M NaCl solutions is compared. The role of dose and implantation current density is studied. Surface analyses of the samples are systematically carried out before and after corrosion tests. The pitting potential of implanted samples is always lower than that of unimplanted ones: the defects generated by the implantation process are probably active sites for pitting. The pit propagation is hindered. The nitrides or α'-martensite layers obtained after elimination of the superficial layers (iron oxide and nickel phase) by electrochemical attack of implanted steel in acidic solution play an important role in this process. (Author)