The electrochemical dissolution of the copper-nickel converter matte is considered as one of the ways of its processing. It is shown that regularities are inherent to the anodic oxidation of this material that are characteristic of its phase components, namely, nickel and copper and nickel sulfides. The sequence of oxidation of phases and the effect of the scan rate of the potential on the limiting oxidation currents and features of formation of the passivation film are established. © Allerton Press, Inc., 2009.