To develop porous alumina supported MF ZrO2 membranes, ZrO2-Al2O3 composite intermediate layers are considered in order to decrease stress creation during the processing and avoid cracks formation. The relation between distortion stress and sintering shrinkage was experimentally studied. And the cracks formation mechanism was qualitatively evaluated and discussed. Finally, crack-free YSZ membrane with pore size of 0.16 mu m on the two ZrO2-Al2O3 intermediate layers possessing a gradient composition was successfully prepared and characterized. (c) 2004 Elsevier B.V. All rights reserved.