A novel modified poly(phthalazinon ether sulfone ketone) membrane has been prepared for application in alkaline direct alcohol fuel cells. These anion exchange membranes with high conductivities and rather low methanol permeability have been prepared by inducting chloromethyl groups and thereby quaternary ammonium groups into the polymer. The reaction products are characterized by FT-IR, thermal analysis and electrochemical methods. The ionic conductivity of the membrane is as high as 0.14 S/cm in 2 mol/L KOH solution at room temperature. The membranes exhibit a thermal stability below 150 degrees C. (c) 2006 Elsevier B.V. All rights reserved.