Abstract: In a system of chemical oxidetion in hte presence of triethanolamine, the mech-anism of chemical oxidation of aluminium is studied by radioisotope tracing, electrochemical measurement, analysis of surface composition, and corrosion test. Theadsorptio nand complexing of the amine and the contribution of OH~- ion to filmforming isemphasized. A preliminary film forming model is put forward,