alloys. The values of the charge transfer resistance R2 were also generally higher in the solutions containing the inhibitor. The CPE constants Y1 and Y2 were almost constant in the solutions with and without the inhibitor. To assign the protective ability of permanganate ions we considered two approaches with R1 and Rct parameters as the calculation basis. In the former case, the inhibitive effect was attributed to an increase in the resistance of the surface oxide/hydroxide film due to the interaction of the permanganate inhibitor with the surface. The same approach will be used in the following section in the analysis and discussion of the DEIS spectra. In the former case, Rct was determined from the experimental data at the low-frequency region when the impedance Z" → 0. In both approaches, IE and Pinh values were calculated on Eqs. ( ) and ( ), respectively. An increase in the amount of the inhibitor in 0.05 M NaCl caused higher extracted values of these two parameters due to the formation of the surface protective films (examined in detail below). The maximum value of IE and Pinh reached 94% and 11.7, respectively (150 mM of KMnO4, AZ31-12Li alloy).