Two kinds of polymers were fabricated and tested as candidates of proton-conducting membranes for polymer electrolyte fuel cell (PEFC) applications. Poly benzimidazole (PBI) and poly(4-phenoxybenzoyl-1,4-phenylene, Poly-X 2000) (PPBP) were sulfonated and characterized as proton-conducting membranes. PBI was sulfonated as PBI-PS (propanesultone) and PBI-BS (butanesultone). PPBP was prepared at various sulfonation levels. Proton conductivities were measured at 60-160 degreesC. Power output characteristics of both polymers were measured by using commercial Pt/C electrodes.