Microstructures of SPEEKK membranes were realized the changes from spheres to nanofibers by introducing electrospinning method into membranes preparation. The SPEEKK membranes with spherical structures exhibit the highest proton conductivity, 0.37 S/cm, which is 37 times as high as the convenient SPEEKK membranes (0.01 S/cm). The membranes prepared by this method should hold immense promise in proton exchange membrane fuel cells applications. (c) 2006 Elsevier B.V. All rights reserved.