Conventional plasma nitriding of stainless steels is carried out at about 550degreesC which leads to an increase of hardness, but also to a decrease of the corrosion resistance. The latter can be avoided by low-temperature nitriding at 380-450degreesC. Anodic behavior of low-temperature nitrided 304L steel was examined here in 0.1 M Na2SO4 at pH 3, 6, and 9, and in 0.1 M Na2SO4 + 0.4 M NaCl at pH 3. The corrosion resistance of nitrided steel was in the chloride-free solution at pH 3 lower than that of unnitrided steel, whereas in the near-neutral solutions the resistance was higher. In the chloride-containing solution, nitrided steel exhibited much higher resistance to pitting corrosion than unnitrided steel. Nitrogen accelerated anodic oxidation in the initial stages of polarization, and promoted the subsequent passivation. X-ray photoelectron spectrometry analysis indicated the presence of nitrogen-rich species and large amounts of hydrated Fe3+/Cr3+ oxides and of Fe3O4/Fe2O3 on corroded nitrided steel. It is proposed that the improved resistance of nitrided steel to pitting corrosion can be related to the enhanced anodic reactivity of nitrogen-containing steel which results in the formation of oxide deposits and also in an accumulation of protective nitrogen-rich species. (C) 2004 The Electrochemical Society.