The fabrication, thermal and proton conducting properties of complex polymer electrolytes based on poly(vinylphosphonic acid) (VPA) and poly(1-vinyl-1,2,4-triazole) (PVTri) were investigated throughout this work. The membrane materials were produced by complexation of PVPA with PVTri at Various concentrations to get PVTriP(VPA)(x) where x designates the molar ratio of the polymer repeating units and varied from 0.25 to 4. The complexed structure of the polymers was confirmed by FT-IR spectroscopy. The TGA results verified that the presence of PVTri in the complex polymer electrolytes suppressed the formation of phosphonic acid anhydrides Lip to 150 degrees C. The DSC and SEM results demonstrated the homogeneity of the materials. Proton conductivity, activation energy and water/methanol uptake of these membranes were also measured. PVTriP(VPA)(2) showed a proton conductivity of 2.5 x 10(-5) S cm(-1) at 180 C in the anhydrous state. After humidification (RH=50%), PVTri-P(VPA)(4) and PVTri-P(VPA)(2) showed respective proton conductivities of 0.008 and 0.022 S cm(-1) at 100 C, where the conductivity of the latter is close to Nafion 117 at the same humidity level. (C) 2009 Elsevier B.V. All rights reserved.