Different post treatment methods such as heat treatment, mechanical processing, sealing etc. are developed to improve microstructure and exploitation properties of thermally sprayed coatings. In this work plasma electrolytic oxidation of aluminium coatings obtained by arc spraying on aluminium substrates is carried out. Microstructure and properties of oxidised layers formed on sprayed coating as well as on bulk material is investigated. The oxidation was performed in electrolyte containing KOH and liquid glass under anodic voltage of 140…210 V, cathodic voltage of 30…50 V, cathodic and anodic current density of 10 А/dm² and process time of 60…260 minutes. It is shown that micro hardness of oxidised layers formed on porous arc sprayed coating as well as on solid material increases strongly. Also, a significant improvement of wear resistance of treated layers under sliding and abrasive wear conditions of more than one order of magnitude compared to hardened bearing steel is observed.