Highly durable quaternary ammonium polyetherketone hydroxide (QAPEK-OH) membranes were developed for alkaline fuel cells operating at elevated temperatures via chloromethylation, quaternization and alkalinization method. The chemical reaction for chloromethylated polymer (CMPEK) was confirmed by nuclear magnetic resonance (H-1 NMR) and the QAPEK-OH membranes were characterized by Fourier transform infrared spectroscopy (FT-IR). The thermal properties of the membranes were determined by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The ion-exchange capacity (IEC), water uptake, mechanical properties and anion conductivity of the QAPEK-OH membranes were measured to evaluate their applicability in alkaline fuel cells at elevated temperature. The anionic conductivity of the QAPEK-OH membrane varied from 8 x 10(-4) to 1.1 x 10(-2) S cm(-1) over the temperature range 20-100 degrees C. The QAPEK-OH membrane showed excellent alkaline stability in 1 M KOH solution at 100 degrees C. The excellent temperature durability of QAPEK-OHs makes them promising membrane materials for alkaline fuel cells. (C) 2011 Elsevier B.V. All rights reserved.