Polymer blend electrolytes composed of poly(acrylonitrile) (PAN) and poly(methyl methacrylate) (PMMA) as host polymers and lithium perchlorate as a salt were prepared by solution casting technique. The electrolytes were prepared for different ratios of host polymers with standard weight ratio of the ionic salt (LiClO4). Among the different concentrations, the polymer electrolyte film containing PAN/PMMA (75:25 wt.%) was found to be a suitable candidate for the battery applications on the basis of ionic conductivity and thermal stability. Complexation, structural reorganizations and ionic conductivity as a function of temperature were studied using X-ray diffraction analysis, Fourier transform infrared, and ac impedance analysis, respectively. Thermal stability of the electrolyte film having maximum ionic conductivity was also studied using thermogravimetric analysis.