We have investigated a method for passivation of InSb by vacuum deposition of SiOxon native oxide layers grown by wet anodization. We show that this multilayer dielectric approach results in improved passivation properties. Results of high resolution Auger spectroscopy reveal important information on the layer structure and composition of this passivation film. Specifically, we report the experimental observation of SiO2formation at the SiOxanodic oxide interface. The interfacial reaction is limited to a thin layer, about 10 nm thick. The SiOxoxidation proceeds by reduction of the native oxide and formation of elemental In and Sb. The electrical features observed in theC–Vcurves (such as flat‐band voltage, hysteresis, low‐frequency‐like response in the inversion region, and other deviations from the ideal curves) are explained in view of the oxidation states of In and Sb, observed at the oxide layers and at their interfaces. These correlations were used for characterization of the desired interlayer parameters.