Gold rotation disk electrode was used to study thiosulfate oxidation processes. The values of current in anode voltammograms measured on the fresh electrode surface are independent of the electrode rotation speed. This means that the rate of the process under study is limited by slow (in comparison with diffusion) heterogeneous reactions. The probable mechanisms of these reactions were analyzed. Voltammograms have a maximum of current and depend on the voltammetric scan rate. The reason of these effects is connected with electrode passivation. (C) 2014 Elsevier B.V. All rights reserved.