Ionic conductivity of poly(ethylene oxide)-lithium trifluoromethanesulfonate (LiCF3SO3 or LiTf) based polymer electrolyte has been increased by incorporating TiO2 nano-filler. Incorporation of 10 wt.% TiO2 exhibited the highest conductivity enhancement with a value of 4.9 x 10(-5) S cm(-1) at 30 degrees C. A further enhancement in conductivity to a value of 1.6 x 10(-4)S cm(-1) at 30 degrees C has been obtained by the incorporation of 50 wt.% ethylene carbonate (EC) plasticizer. Both additives cause a reduction of the PEO crystalline phase content and an increased segmental flexibility leading to conductivity enhancement. Crown Copyright (C) 2014 Published by Elsevier B.V. All rights reserved.