SPEEKK/PANI composite membranes were prepared and characterized for direct methanol fuel cell (DMFC) usages. The morphology change of membranes after the addition of PANI was studied in detail. The result show that: PANI showed very good compatibility with SPEEKK polymers due to the formation of hydrogen bond between the sulfonated acid and anion groups. The composite membranes' structure becomes more compact than that of SPEEKK, which may lead to the decrease of methanol diffusion. The proton conductivity and fuel cell performance of membranes changed a little after the addition of PANi. SPEEKK/PANI composite membranes showed very good prospective in DMFC usages. (c) 2005 Elsevier B.V. All rights reserved.