Composite gel polymer electrolytes (CGPE), with different proportions of poly (ethylene oxide), plasticizers namely 1,3-dioxolane (DIOX)/tetraethelyneglygol dimethylether (TEGDME) and a lithium salt (LITFSI) with the addition of filler chitosan were prepared using the solution casting technique in an argon atmosphere. The membranes were subjected to various characterization techniques such as TG/DTA, FTIR and an ac impedance analysis. A lithium symmetric cell (Li/CGPE/Li) was assembled and the interfacial stability of the polymer electrolyte with a lithium anode was measured. The electrochemical stability and the transport properties of the high conducting sample were also measured. TG/DTA shows the thermal stability of the high conducting sample. The optimal value of the plasticizers was to be found in the ionic conductivity point of view.