Oxygen isotopic exchange has been studied for a number of materials in the BIMEVOX family of compounds. The exchanges were undertaken at 620 degreesC with gold grid electrodes on the samples and with a constant current flowing through the samples during the exchange anneals. These conditions simulate those used when these materials are employed in oxygen separation devices where substantial oxygen fluxes can be sustained using such simple gold grid electrodes.The results showed that samples exchanged under current flow conditions exhibit substantial oxygen exchange at the cathode, in contrast to samples where no electrical bias is applied. This effect was sustained in regions remote from the sputtered gold electrode. Complementary studies of the samples using X-ray diffraction revealed subtle changes in the diffraction patterns following experiments with current flow. These changes are ascribed to a reduction of V5+ to V4+ at the cathode locally transforming the BIMEVOX material into a mixed conducting material, and hence enhancing the oxygen isotopic exchange process. (C) 2003 Elsevier B.V. All rights reserved.