The composition and structure of layers formed by corrosion products at the open-circuit and passive potentials on the surface of steel 3 in aqueous media containing sulfate ions, borate ions, or their mixtures are studied by X-ray photoelectron spectroscopy and secondary ion mass spectrometry. The composition and structure of both the phase surface layers and the adsorption surface layers are found to depend on the solution nature. The composition and structure of a corrosion product layer; the composition of the double layer, in particular, the surface charge and potential; and the anion role as a corrosion inhibitor or activator depend on the way the anion coordinates with the corroding-metal surface. The coordination may be strong, in an inner coordination sphere (borate ions), or less strong, in an outer coordination sphere (sulfate ions) of a cation on the surface.