Abstract: Auger line shape and energy shifts were used to analyze the surface and interface anodic oxides on InP. The composition and bonding of oxides grown in pH=2.6 and pH=6 3% tartaric acid-propylene glyool electrolytes were investigated. Plots of P (LMM) and In (M_4,5N_4,5) Auger line shape and energy shifts provide very useful information in distinguishing between In-0 and In-P or P-0 and P-In bondings. The outer layer of oxides consists of a mixture of In₂O₃ and P₂O₅ Both In -0 and P-O bondings penetrate into the same depth and there is no enrichment of element P on the interface, which is different from thermal oxide on InP. There is no sharp interface between anodic oxide and the InP substract. The method for determining the interface region and initial oxidic processes were discussed.