Diffusion induced grain-boundary migration (DIGM) was observed when 4 and 9 mol% SrO-doped CeO2 (SrDC) ceramics were heat-treated at 1300 degrees C after sintering at 1600 degrees C. In the 9 mol% SrDC specimen, the curvature and distance of boundary migration were increased significantly as the heat-treatment time was increased from 10 min to 10 h at 1300 degrees C. This induced a -2.9-fold increase of the apparent grain-boundary resistivity, which was explained by the physico-chemical change of the grain-boundary structure and/or the current constriction effect due to the undulated boundary morphology. (C) 2010 Elsevier B.V. All rights reserved.