Composite anion exchange membranes were fabricated by simultaneously electrospinning two polymers: chloromethylated polysulfone and polyphenylsulfone. Subsequent processing steps converted the dual fiber mat into a pinhole-free film where an interconnected fiber network of tetramethylammonium-substituted polysulfone is embedded in a polyphenylsulfone matrix. For a composite membrane containing 63 wt% anion-exchange polymer fibers where the fiber IEC was 2.47 mmol/g, the OH- conductivity was high (0.040 S/cm in 23 degrees C water), with significantly less water swelling and better mechanical properties than a neat ionomer film of the same IEC. (C) 2011 The Electrochemical Society. [DOI: 10.1149/2.010203esl] All rights reserved.