[en] Distribution of sulfuric acid electrolyte components over oxide films on aluminium, titanium and tantalum prepared by anodic oxidation in sparking mode has been studied by the methods of X-ray phase and X-ray diffraction analyses. It has been proved that sulfur compounds are incorporated into composition of the coatings produced. The sizes of channels where sulfur involvement occurs have been estimated by recording patterns. Numerical values of the channels obtained by the authors are in a good agreement with literature data. 5 refs.; 4 figs