The blend membranes with partially sulfontated polystyrene (sPS) and partially sulfonated poly(2,6-dimethyl-1,4-phenylene oxide) (sPPO) were prepared and the miscibility between two polymers, was investigated for a cheap proton exchange membrane. In particular, the effects of morphological variation on proton conductivity and methanol permeability for the blends of sPS/sPPO, which have the same ion exchange capacity (IEC), were also investigated. The comparison of Flory-Huggins interaction parameters (chi) between the two ionomers based on the mean-field theory was made from the results of wide-angle X-ray scattering (WAXS) and differential scanning calorimetry (DSC). The transport properties of proton and methanol through the blend membranes were also studied. The blend membranes exhibited relatively higher proton conductivity and methanol permeability than those of single component, sPS and sPPO, respectively. The feasibility test of suitable polymer electrolyte membranes for direct methanol fuel cell (DMFC) was compared with Nafion((R)) 117 (Dupont). (C) 2004 Elsevier B.V. All rights reserved.