Gel polymer electrolytes consisting of 25wt.% P(VdF-co-HFP), 65wt.% ethylene carbonate + propylene carbonate and 10wt.% LiN(CF3SO2)(2) are prepared using by a solvent-casting technique. The electrodes are for use in lithium-ion polymer batteries. The electrochemical characteristics of the gel polymer electrolytes are evaluated by means of ac impedance and cyclic voltammetry. The charge-discharge performance of lithium polymer and lithium-ion polymer batteries is examined. A LiCoO2 vertical bar gel polymer electrolyte (GPE) vertical bar mesocarbon microbeads (MCMB) cell delivers a discharge capacity of 146.8 and 144.5 mAh g(-1) on the first and the 20th cycle, respectively. The specific discharge capacity is greater than 140 mAh g(-1) for up to 20 cycle at all the current densities examined. (c) 2004 Elsevier B.V. All rights reserved.