The oxygen transport properties of the Bi0.775La0.225O1.5 electrolyte material have been investigated. Isotopic exchange depth profiling (IEDP) technique with secondary ion mass spectrometry (SIMS) was used in order to measure the oxygen tracer diffusion coefficient D. The activation energy for oxygen tracer diffusion was found to be 115 +/- 2 kJ/mol (1.19 +/- 0.02 eV). The measured D values were converted using the Nernst-Einstein relationship to conductivity and compared with data from AC Impedance. The agreement of the two sets of data implies that the material is an oxygen ion conductor. (C) 2010 Elsevier B.V. All rights reserved.