New types of composite, solvent-free lithium ion conducting polymer electrolytes have been prepared by dispersing two complementary additives to a PEO-LiX (LiX = LiCF3SO3) matrix. The additives have been chosen in such a way that one of them (calix(6)pyrrole) enhances the lithium ion transference number while the other (super-acid zirconia) enhances the conductivity of the electrolyte. The results demonstrate that these dual-composite polymer electrolytes have a high conductivity with significantly high lithium transference number. This rare combination makes the new polymer electrolytes of interest for the development of advanced, solid-state, lithium polymer batteries. (C) 2007 Elsevier B.V. All rights reserved.