Proton exchange membrane fuel cells (PEMFCs) with Pt/C gas diffusion electrodes and graphite single-serpentine monopolar plates were constructed based on an aromatic poly(etherimide) with isopropylidene groups (PI)/imidazole (Im) and a popular Nafion-115 matrix. The electrochemical properties of PEMFCs were tested at 25 and 608C. The maximum power density of 171 mW/ cm 2 and the maximum current density of 484 mA/cm 2 were detected for Nafion-115/PI membrane. For both constructed PEMFCs the efficiency at 0.6 V was found about 41%. Immersion of Nafion-115 in PI or PI/Im increased the thermal stability and mechanical properties of membranes. Thermal, mechanical properties and morphology of membranes were characterized by TGA, and AFM techniques including force spectroscopy. Interactions between the components in composite membranes were established by FT-IR. V C 2015Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42436.