Composite Polyethylene oxide (PEO)/Cobalt oxide (CoO) electrolyte containing LiClO4 salt forms composite polymer electrolytes (CPE). The ionic conductivity of CPE is noticed to be 1 order greater than PEO-LiClO4 solid polymer electrolyte (SPE) films at room temperature. The CPE films are prepared by solution costing technique. Structural, molecular and thermal properties CPE films are investigated using XRD, FTIR and DSC characterization techniques. XRD, FTIR and DSC spectra of CPE films designates molecular level changes observed in PEO polymer host leading to increased polymer chain movement results in enhanced ionic conductivity. © 2020 Author(s).