Radical copolymerizations of 1-vinyl-2-pyrrolidone (VP) with vinylphosphonic acid (VPA) at different feed ratios were investigated. The copolymers were characterized by H-1-NMR, C-13-NMR and FT-IR. The copolymer composition was determined from the elemental analysis. Thermogravimetric analysis (TG) illustrates that the copolymers are stable up to 200 C. Temperature dependence of the alternating current (AC) conductivities were investigated by means of impedance spectroscopy. The direct current (DC) conductivities of the samples are derived from the AC conductivity data. (C) 2004 Elsevier Ltd. All rights reserved.