20mol% erbia stabilized bismuth oxide (ESB) in the cubic fluorite structure is one of the highest oxygen ion conductors known. On annealing at temperatures below the transition temperature (similar to 600 degrees C), a fast continuous decay in oxygen ion conductivity occurs which has been attributed to the occupational and positional ordering on the oxygen ion sublattice. The reverse transition is characterized by the enthalpy required to disorder the ordered lattice. This study looked into the effect of direct current bias on the ordering kinetics of ESB solid electrolytes using symmetrical cells consisting of Ag-ESB cermet electrodes. Electrochemical impedance spectroscopy studies showed that on isothermal annealing at 500 degrees C. the current bias does not have a significant effect on the conductivity decay, though the differential scanning calorimetry (DSC) studies showed that under bias the endotherm related with the reverse transition appeared at shorter annealing time periods. Ag-ESB electrodes showed good performance, though were unstable at 625 degrees C under higher bias currents due to the Ag electromigration along with the oxygen flux. (c) 2006 Elsevier B.V. All rights reserved.