Novel composite polymer membranes for fuel-cell applications were prepared by solution blending sulfonated poly(ether ether ketone) (sPEEK) and polyacrylonitrile (PAN) in DMF and heating under nitrogen at 380 degrees C. The incorporation of PAN into sPEEK membranes significantly reduced the swelling in hot water and decreased methanol permeability of the membranes. An optimum ratio of sPEEK and PAN for proton conductivity was found making this system competitive to that of Nafion membranes at room temperature. As a result, for polymer electrolytes, sPEEK/PAN composite membranes offer a possible low-cost alternative to Nation membranes. (c) 2007 Elsevier B.V. All rights reserved.