On the basis of analysis of scientific papers and experimental data, possible mechanisms of anodic formation of oxide compounds (by the example of Со2О3) and relevant phase transformations during electrolysis in the aqueous solution of cobalt sulfate are described. Mechanism of anodic formation of Со2О3 molecules with involvement of adsorbed oxygen and phase formation process, taking into account volumetric structure of oxide molecules, is offered. The surface morphology of investigated sediments proves that they are built up by means of step growth of crystals and formation of large-sized crystal grains displaying certain tendency to spheroidization. Proceeding from Gibbs-Thompson equation for electrochemical system which correlates the value of electrode potential with radius and specific free surface energy of the nucleus, possible energy relations of anodic nucleation of metal-oxide compound are considered.