A series of side-chain-type sullonated poly(ether ketone/ether benzimidazole)s containing side chain sullonate groups and main chain benzimidazole rings were successfully synthesized via benzimidazolization and acylation in a one pot method. By varying the amount of sulfonate monomers, the ratio of sullonate acid unit to benzimidazole base unit was easily controlled.H-1 NMR and IR spectra were used to characterize the polymer structure. The resulting membranes exhibited excellent mechanical properties (11-45 MPa tensile stress and 9-23% elongation at break) and good thermal stability. The proton conductivity of SPEKEBI-4 was 136 mS cm(-1) at 30 degrees C, much higher than Nafion (R) 115 membrane; while the methanol permeabilnies of all the membranes were lower than Nafion (R) 115 membrane. Moreover. the passive direct methanol fuel cells (DMECs) with SPEKEBI-2 membrane exhibited a maximum power density of 39.3 rnW cm(-2) at 25 degrees C, which show great potential for application in polymer electrolyte membrane fuel cells. (C) 2014 Elsevier B.V. All rights reserved.