The EIS is a well-known and widely used measurement technique for corrosion monitoring of Mg alloys, which, however, raises some ambiguity in the qualitative and quantitative interpretation of the obtained data, especially in a low-frequency domain . Therefore, the ultimate challenge of EIS characterization of Mg alloys is to minimize the impact of the nonstationarity of the measurement on the obtained spectrum. This is especially important in the case of lightweight Mg alloys containing Li, since their corrosion rates are usually high . The rational approach is to decrease the measurement duration while maintaining a reasonable frequency interval or, more promising, measuring spectra in the multisine mode . In this section, we discuss EIS spectra obtained by the classical EIS approach and compare these results with those obtained by the multisine approach of dynamic multifrequency EIS measurement (DEIS) .