Solid polymer electrolyte films of polyvinylpyrrolidone (PVP), and poly(vinyl alcohol) (PVA) with KClO3 and KClO3+plasticizer (dimethyl formamide) have been prepared by the solution - cast technique. Various experimental techniques such as electrical conductivity (composition dependence) at room temperature and transport number measurements are used to characterize these polymer electrolyte films. Electrochemical cells of configuration K|(PVP+PVA+KClO3)|(I2+C+electrolyte) and K|(PVP+PVA+KClO3+plasticizer)|(I2+C+electrolyte) have been fabricated. The discharge characteristics of the cells are studied under a constant load of 100kΩ. The open-circuit voltage, short-circuit current and discharge time for the plateau region are measured. The PVP+PVA+KClO3 blend polymer electrolyte system with added plasticizer shows an increased discharge time with respect to the pure PVP+PVA+KClO3 blend polymer electrolyte system.