Bi2Ru2O7 and Bi3Ru3O11, have been tested as electrodes on stabilized zirconia at temperatures as low as 500 K. The oxides have been characterized by thermogravimetry under controlled oxygen partial pressure at high temperature and by potentiometric measurements after controlled cathodic polarization. The oxygen electrode reaction as functions of oxygen pressure and temperature has been studied by impedance spectroscopy. At low temperature, the dependence of the polarization resistance on the oxygen pressure was analyzed in terms of charge transfer as a rate controlling step.