Sulfonated poly(styrene-ethylene/butylene-styrene) (S-SEBS) polymer was synthesized by grafting sulfonic groups onto SEBS triblock copolymer with acetyl sulfate as the sulfonating reagent. Effects of sulfonation reaction time, temperature, and the amount of sulfonating reagent on sulfonation degree were investigated. S-SEBS membranes with different sulfonation degrees were prepared and characterized by various techniques including FTIR, SEM, EDS, TG and DSC Tensile strength, water sorption measurement and contact angle goniometry were also applied to investigate the mechanical property and hydrophilicity of S-SEBS membrane. Membrane performance for water desalination by vacuum pervaporation was investigated as a function of sulfonation degree, feed concentration, temperature, and feed flow rate. Results indicated that the hydrophilicity, water permeate flux and anti -fouling property of the membrane increased remarkably with the sulfonation degree. The majority of rejection to various salts was over 99% and all were above 98.4% irrespective of sulfonation degree of S-SEBS. The membrane with 54.1% sulfonation degree showed a high water flux of 22.87 kg/m(2). hat 63 C and 6 kPa permeate pressure for a 1 wt% NaCl feed solution. The membrane exhibited good restorability of water flux after acid cleaning. (C) 2016 Elsevier B.V. All rights reserved.