The sulfonated poly(phthalazinone ether ketone) (SPPEK) membrane and quaternized poly(phthalazinone ether ketone) (QPPEK) membrane were prepared by the casting method from corresponding materials. Suitable thermal and mechanical properties of modified PPEK membranes were proved by thermogravimetry analysis and tensile machine. The ionic conductivities and methanol permeabilities of the two kinds of membranes were tested and compared with each other. The proton conductivity of SPPEK membrane and the hydroxide ion conductivity of QPPEK membrane reached respectively the maximum of 0.031 S/cm at 95 degrees C and of 0.014 S/cm at 80 degrees C under 100% relative humidity. Both the methanol permeabilities at room temperature were lower than that of Nafion117. (C) 2008 Elsevier B.V All rights reserved.