A composite polymer electrolyte system based on PEMA/PVAc/LiClO4/EC with different wt% of nano filler TiO2 was prepared by solution casting technique.The structural investigations of the prepared polymer electrolyte membranes were carried out using X-ray diffraction and Fourier Transform infrared spectroscopictechniques. The electrical measurements were performed at various temperatures 303363 K using ac impedance technique. The maximum room temperature ionic conductivity of 2.745 x 10(-3) S/cm was obtained for the polymer electrolyte membrane with 10 wt% TiO2. The temperature dependent ionic conductivity plot exhibited VTF behaviour. The porous nature of the membranes was verified from the SEM and AFM images. The thermal investigations performed on the samples by DSC technique displayed prominent endothermic peaks which revealed that the samples with the incorporation of filler had undergone a transition tothe amorphous phase at lower temperatures. The thermal stability of the film (F3) of maximum ionicconductivity was found to be 260 degrees C by means of TG/DTA analysis. The wide electrochemical stability window of -2.1 V to +2.1 V and the cyclability & reversibility of the maximum ion conducting sample at ambient temperature were confirmed by carrying out the electrochemical characterizations such as linear sweep voltammetry and cyclic voltammetry respectively. (C) 2017 Elsevier B.V. All rights reserved.