Industrial usage of Plasma Electrolytic Oxidation (PEO) has grown consistently in recent years, thanks to the improved characteristics imparted to the oxide film in terms of surface adhesion, hardness, crystallinity, uniformity, and corrosion resistance. The metallic substrate is not subjected to elevated temperature and the overall equipment complexity is relatively simple, making the technique a good candidate for surface functionalization. In PEO treatments, high voltages are employed (~ 150-750 V 1) allowing for the formation of an insulating, or at least semiconductive, oxide layer that’s limits ion transport responsible for the initial coating growth. Beyond the spark voltage (prerequisite the enter the PEO regime) oxidation does not occur only as the result of a continuous flow of ions but rather it takes place after the cooling of a plasma discharge.