This study deals with the separation of dimethyl carbonate (DMC) by pervaporation using crosslinked chitosan membranes. DMC, an environmentally benign chemical, is commercially produced by oxidative carbonylation of methanol, and the separation and purification of DMC is critical to DMC manufacture due to azeotropic nature of the reaction mixtures. In this study, chitosan membranes crosslinked by dilute sulfuric acid were prepared for DMC separation by pervaporation. The membranes were tested for separation of binary DMC/water, DMC/methanol and methanol/water mixtures and ternary DMC/methanol/water mixtures in a temperature range of 25-55 degreesC. The experimental results showed that the membrane could be used effectively to break the DMC/methanol azeotrope and to remove a small amount of water from DNIC. It was also shown that coupling effect was important in pervaporation separation of multi-component mixtures due to interactions among the permeating species. (C) 2002 Elsevier Science B.V. All rights reserved.