Abstract: A kind of symmetrical electrochemical cell of the type M, M_xO_y|ZrO₂(MgO)| M, M_xO_y was used to study the polarization characteristic of solid state reference
electrodes at high temperature. Experimental results show that the variation of overpotential with polarization current is linear. The exchange current
desities for the Mo/MoO₂, Cr/Cr₂O₃, Ni/Ni/O and Co/CoO electrodes, in the order named, are decreasing. The exchange current densities of all kinds of
electrodes are also increasing with the increase of metal ratio in reference electrodes and temperature. The activation energy of the electrode reactions was calculated.

Key words: zirconina, solid state reference electrode, exchange current density