Polyphosphazene nanotubes (PZSNTs) were incorporated into polydimethylsiloxane (PDMS) membranes to form nanocomposite membranes. SEM characterization showed that PZSNTs were well dispersed in PDMS. The nanocomposite membranes exhibited higher separation factor for water-ethanol mixture compared with PDMS membranes. As PZSNT content increased, the selectivity increased and permeation flux increased at first to a maximum value and then almost kept the same. The decrease of nanotube diameter caused an increase of permeation flux and separation factor. The effects of temperature and feed solution concentration on pervaporation properties were also investigated. Sorption measurements explained the pervaporation results well. (C) 2009 Elsevier B.V. All rights reserved.