A range of gel electrolytes, composed of a hydroxypropylcellulose ester with poly(oxyethylene) side chains, LiCF3SO3 and propylene carbonate (PC), or a mixture of propylene carbonate with ethylene carbonate (EC), were prepared and studied. The conductivities of gels containing 10 wt.% LiCF3SO3, and having propylene carbonate concentrations varying from 20 to 70 wt.%, exhibit Arrhenius behaviour with activation energies ranging from 16 to 34 kJ mol(-1). Room temperature conductivities of the order of 10(-3) S cm(-1) are achieved with propylene carbonate contents above 50 wt.%. Gels containing 70 wt.% propylene carbonate, or a mixtures of propylene carbonate and ethylene carbonate, were cross-linked to form elastomeric films exhibiting good mechanical properties and room temperature conductivities of similar to 10(-3) S cm(-1). The conductivities and mechanical strength of these films increased with increasing ethylene carbonate content. An Arrhenius dependence of log conductivity on (1/T) is also observed in these films, with activation energies for ion transport around 16 kJ mol(-1). (C) 2003 Elsevier Science B.V All rights reserved.