Abstract: The voltammetric characteristics of RuO_2 electrode has been studied by means of cyclic voltammetry and pulse polarography. In the potential range of 0.2-0.8 V, there are two redox reactions as follows:
RuOOH<+>RuO_2+H~++e
RuO_2+H_2O<=>RuO_3+2H~++2e
but not one redox reaction to turn Ru~(3+) into Ru~(4+).
The oxygen-deficient structures are the active sites whose disappearance results in the deactivation of the electrode.