Acid-base polymer blends for polymer electrolyte membranes have been prepared by blending sulfonated poly(ether ether ketone) (SPEEK) with poly(vinylpyrrolidone) (PVP) to reduce methanol uptake and to decrease methanol permeability while maintaining high proton conductivity. The acid-base interaction occurring on the sulfonic acid group and on the tertiary amide group was characterized by FTIR and DMA. As the composition of PVP lowered than 20 wt % in the blends, the acid-base interaction causes great reduction on methanol uptake and the methanol permeability; however, the proton conductivity is still high. In this work, membrane-electrode assemblies (MEAs) have been prepared for direct methanol fuel cell (DMFC) from both blend membrane and Nafion 117. DMFC single cell performance was also evaluated. Results confirmed that SPEEK (with the degree of sulfonation (DS) = 69%) blended with PVP (M. = 1,300,000) with a ratio of 80/20 (w/w) exhibits higher open-circuit voltages (OCV) and lower polarization loss than those of Nafion 117. These acid-base blends will be suitable for DMFC application. (c) 2005 Wiley Periodicals, Inc.