A series of copolymers were produced by conventional free-radical polymerization of ethyleneglycol methacrylate phosphate (EGMAP) and 4(5)-vinylimidazole (4-VIm) at several feed compositions using DMF as solvent. The copolymers were characterized by H-1 NMR and FT-IR. Copolymer compositions were obtained by elemental analysis. Reactivity ratios of the monomers are equal to: r(1) = 0.12 +/- 0.03 and r2 = 0.19 +/- 0.05 for 4-VIm-EGMAP system that exhibited an alternating behavior. Thermal properties of the dry copolymers were investigated via thermogravimetry analysis (TG) and differential scanning calorimetry (DSC). The ion exchange capacity (IEC) and anhydrous proton conductivities of the samples were measured and analyzed according to copolymer composition. (C) 2007 Elsevier Ltd. All rights reserved.