A series of sulfonated poly(ether ketone ketone)s (SPPFEKKs) containing both of phthalazinone and hexafluoroisopropylidene moieties were synthesized by direct nucleophilic polycondensation reaction from 4-(4-hydroxyphenyl)-1(2H)-phthalazinone (DHPZ), 4,4-hexafluoroisopropylidene-diphenol (BPAF), 1,4bi(4-fluorobenzoyl) benzene (DFKK) and 1,4-bi(3-sodium sulfonate4-fluorobenzoyl) benzene (SDFKK). The obtained SPPFEKKs had high molecular weight with inherent viscosity ranged from 1.29 to 1.53 dL/g and their chemical structure was characterized by Fr-IR and H-1 NMR. The ionic membranes of SPPFEKKs showed high proton conductivity, for instance, SPPFEKK-120 (DS = 1.20) demonstrated 1.0 x 10(-1) S/cm proton conductivity at 95 degrees C, which was very close to that of Nafion (R) 117. All the SPPFEKK membranes exhibited methanol permeability lower than 2.76 x 10(-1) cm(2)/s, which was much lower than that of Nafion (c) 117 (2.38 x 10(-6) cm(2)/s). These copolymers also showed excellent thermal stability and good solubility in aprotic polar organic solvents. The ionic membranes of SPPFEKK demonstrated tensile strength varied from 57 to 69 MPa depending on their DS. (c) 2008 Elsevier B.V. All rights reserved.