The study of the InAlAs surface oxidation process in the Townsend gas-discharge plasma of gas-mixture Ar, O2, CF4 at room temperature was performed. The anodic layer thickness distribution, the morphology of InAlAs surface and anodic layer/InAlAs interface, as well as the layer chemical composition, were investigated by scanning ellipsometry, AFM, HREM and XPS methods. It was shown that the presented oxidation technique provides a controlled formation of non-fluorinated and fluorinated anodic layers on the InAlAs surface with a sharp interface and unchanged surface morphology. The non-fluorinated anodic layer mainly consists of semiconductor element oxides (In2O3, Al2O3, As2O3). The oxidation in the fluorine-containing medium leads to the formation of In, Al and As oxyfluorides.