A series of phosphazene heteropolymers (NP (OC6H4C3H5)(x)(OC6H5)(y)(OR)(z))(n) were synthesized, where different pendant groups (-OC2H5, -OCH2CF3 and -OCH2CF2CF2CF2CF2H) providing hydrophobic property were used. All the polymers are amorphous materials with good film forming property. Pervaporation experiments were performed to characterize the polymer membranes. The results showed that poly-organophosphazene material with -OCH2CF3 group had the best membrane separation performance for ethanol/water mixture under the same content of hydrophobic group. Solubility parameters calculation and sorption measurement were also performed to study the structure-performance relationship. (C) 2009 Published by Elsevier B.V.