The analysis of the EIS response of passive film remains a difficult challenge since it usually results in a non-ideal behavior of the dielectric properties of the film and mainly relies on the assumption that the contribution of the double layer can be neglected. The later an approximation can be verified a posteriori when data analysis is performed assuming that each of the contributions is a capacitance and that the order of magnitudes for the double layer capacitance is between 10 to 50 µF cm-2 for a wide range of electrolyte concentrations and over a large potential window. However, both the electrochemical impedance of passive film and double layer relaxation usually exhibit a non-ideal behavior, thus resulting in the use of constant-phase elements (CPE) to account for the distribution of dielectric properties of the interface as well as experimental factors (position of the reference electrode, adsorption of impurities…). Moreover, the frequency dispersion that can be observed in the high frequency domain adds to the complexity of this analysis [1]. We present in this work, how to use the graphical analysis of the experimental data in the different frequency ranges, including the low-frequency domain, in order to determine the values of the capacitances without resorting to fitting procedures involving complex functions. This analysis is based on the electrical description of the interface presented in Fig. 1 [2]. It will be shown that such an approach allows determination of the thickness of a thin layer at the interface, independently of the use of a CPE to describe the distribution of time constants. This will be first demonstrated on synthetic data and then used for the determination of the oxide film formed on Al electrode. References [1] O. Gharbi, A. Dizon, M.E. Orazem, M.T.T. Tran, B. Tribollet, V. Vivier, From frequency dispersion to ohmic impedance: A new insight on the high-frequency impedance analysis of electrochemical systems, Electrochim. Acta, 320 (2019) 134609. [2] O. Gharbi, M.T.T. Tran, M.E. Orazem, B. Tribollet, M. Turmine, V. Vivier, Impedance Response of a Thin Film on an Electrode: Deciphering the Influence of the Double Layer Capacitance, Chemphyschem, 22 (2021) 1371-1378.