For the AZ31-4Li alloy, the track of the pH changes in solutions containing 5 mM of KMnO4 was comparable to that in the solution without the inhibitor. At higher concentrations of KMnO4, the values of the pH were generally slightly higher. For the AZ31-8Li, the values of the pH were smaller in the case of KMnO4 concentrations of 5-50 mM, while for 100 and 150 mM the values were comparable to those in 0.05 M NaCl solution. For the AZ31-12Li alloy, the final values of pH were lower for all examined concentrations of KMnO4. For all alloys, the stability of pH values in Mn-containing solutions after ca. 400 s of exposure suggests the formation of a surface protective film.