The inhibition and stimulation of anodic and cathodic processes for the iron corrosion in a 1 M HClO₄ solution with various inorganic anions and/or tetra-n-butylammonium cation, TBA⁺ and the adsorption of these ions on the iron surface were studied by impedance and polarization measurements. The anions, Cl^-, Br^-, I^-, SO₄^2-, and N₃^-inhibited and S₂O₃^2-, SH^-, SCN^-, and NO₃^-stimulated both the anodic and cathodic reactions. The double layer capacitance showed that I^-, S₂O₃^2-, SH^-, and SCN^-were readily adsorbed on the surface over the whole range of potential examined. The joint adsorption and synergistic inhibition effect of the anion and TBA⁺ were observed mostly in the potential range near the corrosion potential and in the region of anodic polarization. Mechanisms of the inhibition and stimulation of iron corrosion by the adsorption of these ions are discussed in terms of the kinetics of the anodic and cathodic processes based on Frumkin adsorption.