A Nafion membrane with enhanced performance has been prepared by using a novel casting solution containing low-polarity nonsolvent tetrachloroethylene (TCE). ICE induces self-organization of the ionomer and turns the originally transparent Nafion in dimethylformamide (DMF) solution into opaque. The Nafion membrane cast from such opaque solution remains mechanically robust and shows a proton conductivity of 0.07 S cm(-1) at room temperature, and 0.21 S cm(-1) at 80 degrees C under saturated humidity, which is an increase of 62% and 103% respectively over the membrane without ICE involvement. Besides, water content and water permeability of the new membrane become higher. The enhanced membrane performance is attributed to larger clusters of sulfonate groups in Nafion, which is revealed by small-angle X-ray scattering (SAXS) and transmission electron microscopy (TEM). (C) 2013 Elsevier B.V. All rights reserved.