Microhardness is a basic controlled quality parameter according to functional coatings, which is linked with a number of physico-chemical properties, such as coating strength, abrasion resistance, resistance to deformation, life. Life of the coating from a diagnostic point of view is influenced by chemical, physical, technological and material conditions of the process of creating film. The paper deals with analysis of the microhardness coating created by anodic oxidation of aluminum with a direct link to the chemical and physical factors controlled by the Design of Experiments methodology at constant anode current density 2 A.dm-2. © (2013) Trans Tech Publications, Switzerland