This paper reports the sol-gel preparation and subsequent characterization of ceramic multilayer membranes, comprising a mesoporous gamma-Al2O3 or ZrO2 interlayer and a microporous ZrO2 toplayer. The optimized membranes show a molecular weight cut-off (MWCO) of 200-300 in standard nanofiltration tests after firing the ZrO2 toplayer at 400 degrees C. For the all-ZrO2 membrane, a detailed study was made of its corrosion behaviour. PEG-retention, MWCO and permeability were studied in dynamic corrosion tests using aqueous solutions both at low and high pH values. Long-term corrosion tests (4 weeks) at successive pH values of 2, 13 and 1 demonstrated no significant loss in performance for the membranes showing a MWCO in the range 200-300. (c) 2006 Elsevier B.V. All rights reserved.