Different types of membranes based on polyelectrolytes were developed for the separation of aromatic-aliphatic hydrocarbon mixtures by, pervaporation (PV). For that purpose. composite membranes with different polyelectrolytes, soluble either in water (Sulfoethylcellulose) or in ethanol (custom-made copolymers of methyl methacrylate (MMA) and methacrylic acid [3-sulfo-propyl ester] potassium salt) were prepared by an interfacial reaction with oppositely charged ionic surfactants. The latter copolymer could also be, cross-linked with Col ions. Both membrane types show a clear enrichment of aromatic components (toluene or benzene) in the course of the PV process (from 20 wt.% in the feed to about 55 wt.% in the permeate). The fluxes are in the range of 1 kg/hm(2) at a feed temperature of 80 degreesC. The separation of a benzene/cyclohexane mixture was also successful at 50 degreesC. In all cases. higher fluxes were obtained with benzene/cyclohexane feed mixtures than with toluene/heptane mixtures. Also, in multi-component feed mixtures, benzene exhibit the better permeate rates. (C) 2004 Elsevier B.V. All rights reserved.