Composite polymer electrolytes (CPE) composed of Poly (vinyl acetate) (PVAc), poly (vinylidenefluoride-co-hexafluoropropylene) (PVdF-co-HFP), barium titanate (BaTiO3) nanofiller, lithium tetrafluroborate (LiBF4), ethylene carbonate (EC) and propylene carbonate (PC) were prepared using simple solution casting method. The BaTiO3 nanofillers were homogeneously dispersed in the polymer electrolyte matrix and exhibited excellent interconnection with PVAc/PVdF-co-HFP/EC/PC/LiBF4 polymer electrolyte. The addition of BaTiO3 nanofillers improved the ionic conductivity of the polymer electrolytes to some extent when the content of the BaTiO3 is 8 wt%. The addition of BaTiO3 also enhanced the thermal stability of the electrolyte. The structural and complex formations of the composite electrolyte membranes were confirmed by X-ray diffraction and FTIR analysis, respectively. Surface morphology of the samples was depicted using scanning electron microscope and atomic force microscope studies. (C) 2012 Elsevier B.V. All rights reserved.