A combination of Fabry-Pérot interferometry and the DC electrochemical method have been used for the first time, in situ, to measure the anodic current density of aluminium oxide films in 0,6, and 10% sulfuric acid solutions (H₂SO₄). The calculated values of the anodic current density by Fabry-Pérot interferometry were verified by the DC electrochemical method and the electrochemical impedance spectroscopy (EIS). The corresponding thickness of the aluminum oxide film to the anodic current density was determined by Fabry-Pérot interferometry under a potentiolstatic potential of 9 V with respect to the open circuit potential of the aluminum samples in the H₂SO₄ solutions, for 90 minutes. The obtained thickness of the aluminum samples by Fabry-Pérot interferometry was verified by sanning electron microscopy(SEM) and compared to values that were obtained by the EIS. The calculated anodic current density by Fabry-Pérot interferometry was found in ageement with those of the DC electrochemical method. In contrast, the calculated anodic current density by Fabry-Pérot interferometry was found in a slight discrebancy with data obtained by the EIS.

Keywords. Aluminium, Aluminum oxide film, Fabry-Pérot interferometry, Electrochemical impedance spectroscopy (EIS), Anodic current density, and Sulfuric acid.