Sulfonated polyimide (SPI) membrane has been evaluated as an electrolyte membrane for direct methanol fuel cells (DMFCs) in comparison with Nation((R)) 112. The membrane-electrolyte assemblies (MEAs) were made by hot-pressing each membrane, an anode of Pt-Ru dispersed on carbon black (PtRu/CB) and a cathode of Pt/CB with Nafion((R)) ionomer. The cell prepared with SPI membrane exhibited a suppressed methanol crossover to a half of Nation((R)) 112, resulting in the improved cell performance.