This paper presents a one-period energy method of studying the electrochemical corrosion phenomena that occur on metal surfaces. The method employs the energy state variables (time functions) to determine whether the material is susceptible to corrosion. The main feature of this approach is the elimination of the frequency analysis, and thereby gives significant simplifications of the corrosion rate measurement. Another important feature is that the method is based on an analysis of the appropriate loops on the energy phase plane which results in the corrosion process being easily estimated through the evaluation of the loop area. The physical results obtained by this method are easily interpretable with robust properties. The usefulness of the proposed technique was examined in microcrystalline and nanocrystalline copper layers deposited on a polycrystalline substrate by the electrocrystallization method. The quantitative results obtained from the measurements of the one-period energy loops are used for controlling the corrosion resistances of the micro- and nano-copper thin-layer coatings. Several experiments performed on real specimens verified the effictiveness of the method as used for analysing the electrochemical corrosion in many practical systems. We have shown that the corrosion resistance of the nanocrystalline copper layers is worse than that of microcrystalline copper layers even when the layers of the two types are produced by the same electrochemical method.