This paper report the synthesis and properties of a series of 
composite polymer electrolytes formed by dispersion of 
tetraethylene glycol dimethyl ether (TEGDME) into poly (vinyl 
alcohol) complexed with magnesium salt. Scanning electron 
microscope (SEM) images of different TEGDME concentrations 
of films revealed that TEGDME dissocit the agglomeration of salt 
and some pores appers at the surface. The addition of TEGDME
greatly enhances ionic conductivities of the electrolytes which is 
due to the high polarity and diffusivity of TEGDME. The
optimum ionic conductivity value of the plasticized polymer
electrolyte film of 1 wt.% TEGDME has been achieved to be of
the order of 10-6
S.cm-1
at room temperature. Dielectric properties
have been studied for different wt.% of plasticizer and their
variations have been observed.