In the goal to obtain high rejection rate of anions in electrolyte solutions and to filter concentrated solutions, the sol-gel route was used to prepare ceramic membranes using the Nasicon (Na3Zr2Si2PO12) material, which presents a high charge density. Confronted to the difficulties to synthesise a Nasicon membrane by slipcasting, we have used mixed Nasicon-ZnAl2O4 sols of different compositions to prepare the membranes. The first filtration. test results are in agreement with the measurements of the electrophoretic mobility of the material powders. (C) 2003 Elsevier Science B.V. All rights reserved.