Nanocomposite polymer electrolyte (NCPE) films of [75 wt % poly(ε‐caprolactone) : 25 wt % zinc triflate] + x wt % nanofiller Al2O3 (x = 1, 3, 5, 7) were prepared by solution cast technique. Such NCPE films were characterized using Fourier transform infrared and AC impedance spectroscopic techniques. Complexation of polymer with salt and nanofiller was revealed from FTIR analysis. On the other hand, an apparent increase in the number density of charge carriers upto 5 wt % loading of the nanofiller was also confirmed. Furthermore, AC impedance spectroscopic studies have shown that ionic conductivity increases with the addition of Al2O3 and reaches a maximum of 2.5 × 10−5 S cm−1 at room temperature for 5 wt % loading of nanofiller. The dielectric behavior of all the synthesized samples has also been analyzed and presented. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40524.