The study presents the characteristics of obtaining oxide layers of Al2O3 on AlMg2 aluminium alloy, as a result of oxidation through the electrolytic method, in ternary electrolytes. The dependency between the production of oxide layers and the length of the aliphatic chain of the dicarboxylic acid has been determined. The chemical composition of the oxide layers has been presented, and a comparison has been made with the results of stoichiometric calculations of the Al2O3 layer. The phase composition of the oxide layers obtained has been examined, using the X-ray diffraction. It has been found that oxide layers obtained using the electrolytic method in ternary electrolytes are completely amorphous. Also, examinations of the structure of layers of Al2O3 obtained on AlMg2 aluminium alloy.