The OCP profiles (Fig. ) showed similar tendencies. The lowest values of the OCP were observed in the 0.05 M NaCl solution without the inhibitor. In the presence of the molybdate inhibitor, the OCP was shifted to more positive values at the outset of the exposure of all alloys, suggesting rapid adsorption of molybdate ions on the surface and the retardation of the anodic process . At low concentrations of the inhibitor (10 mM), some small but distinct potential fluctuations were observed for the AZ31-8Li sample, which might be a sign of a less stable surface film and local corrosion attack. The value of the stabilized OCP increased with increasing the molybdate concentration in the solution. The OCP profiles suggest that at high concentrations the molybdate inhibitor rapidly forms a stable film over the surface of all examined alloys, which shifts the electrode potential in the noble direction. retardation of anodic kinetics and improved corrosion resistance. However, in this case, it was followed with an almost an order of magnitude increase in the icorr values. This inconsistency can be explained by either different phase composition of the alloys' matrix, i.e. different thermodynamic probability of corrosion, or the so-called cathodic activation phenomenon, observed in the course of corrosion of Mg alloys . The comparison of anodic and cathodic Tafel slopes (Table ) shows that corrosion kinetics is mostly controlled by the cathodic process and anodic reaction has little impact on the OCP . The polarization curves obtained in molybdate-containing 0.05 M NaCl solutions showed a notable change in the kinetics of the anodic and cathodic processes. The corrosion potential was shifted towards more noble values in the presence of the inhibitor. This shift was larger as the concentration of the inhibitor in the solution increased and, in this case, was directly associated with the interaction of the molybdate inhibitor with the surface of the alloys and retardation of the corrosion kinetics. The maximum difference between Ecorr in the inhibited and reference solutions decreased as the amount of Li in the alloy increased and was ca. 140, 100, and 65 mV for AZ31-4Li, AZ31-8Li, and AZ31-12Li alloys, respectively. Furthermore, starting from 50 mM of added molybdate it was possible to mark the change in the slope on the anodic branches of the polarization curves recorded for AZ31-8Li, and AZ31-12Li alloys, corresponding to the breakdown potential, Ebr. This provides additional evidence for the formation of a protective layer on the surface under these conditions.