Polymer electrolytes based on polyvinyledene fluoride (PVdF) and ammonium fluoride (NH₄F) have been prepared and characterized. Films of polyvinyledene fluoride and ammonium fluoride have been prepared by solution casting technique using tetrahydrofuran (THF) as a solvent. Maximum conductivity of 1.17 x 10^-7 S/cm at room temperature has been obtained for polymer electrolytes containing 10wt% NH₄F. The conductivity of polymer electrolyte has been increased by three orders of magnitude from 10^-7 to 10^-4 S/cm with the addition of dimethylformamide (DMF) as plasticizer. The increase in conductivity has been explained to be due to the dissociation of undissociated salt/ion aggregates present in the polymer electrolytes with the addition of high dielectric constant plasticizer (DMF). Maximum conductivity of 1.26 x 10^-4 S/cm has been observed for plasticized polymer electrolytes. The variation of conductivity with temperature suggests that these polymer electrolytes are thermally stable and small change in conductivity with temperature is suitable for their use in practical applications like solid state batteries, fuel cells, electrochromic devices, supercapacitors etc.