The corrosion behaviour of naval steels is characterized by cyclic voltammetric profiles, open-circuit potential decays and polarization curves in 0.5 M sodium nitrate and in 0.6 M sodium chloride at 20 degrees C. Naval steel surfaces can be modified by the application of periodic symmetric and/or asymmetric potential routines in strong alkaline solutions. These perturbations produce the formation of protective or non-protective surface oxides, which can be characterized by scanning electron microscopy and cyclic voltammetry. Corrosion parameters of the new surface oxides are evaluated by polarization curves after long-time exposures in electrolytes containing sodium chloride and sodium nitrate.