Nanocomposite membranes of sulfonated polyether ether ketone (sPEEK) are prepared with polyaminobenzene sulfonic acid grafted single-walled carbon nanotubes copolymer (PABS-SWCNT) and its zwitterion interactions are studied. The nanocomposite membranes are prepared through solution cast technique using PABS-SWCNT as additive in different weight % (0.1, 0.15, and 0.2) ratio. The additive and nanocomposite membranes are characterized for its surface morphology, composition, thermal and physico-chemical properties. The nanocomposite membrane comprising optimized content of PABS-SWCNT (0.15 wt %) shows improved proton conductivity and reduced methanol crossover resulting in enhanced DMFC peak power density of 150 mW cm(-2) in comparison to 110 mW cm(-2) for sPEEK and 80 mW cm(-2) for Nafion (R) 117 respectively. The improved durability till 100 h for sPEEK/PABS-SWCNT (0.15 wt %) compared to sPEEK and Nafion-117 confirms its viability in DMFC application. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.