Hybrid, solid polymer electrolyte films consisting of poly(vinyl chloride) (PVC), poly(methyl methacrylate) (PMMA), LiBF4, and dibutyl phthalate (DBP) are described. FTIR studies and electrical conductivity measurements are carried out. The temperature dependence of ionic conductivity of the polymer films is explained on the basis of a free volume model. Conductivity studies of PVC-PMMA-LiBF4-DBP complexes have been investigated at different salt concentrations. The highest ionic conductivity value (2.482 X 10(-5) S cm(-1)) is obtained for 8 mole ratio of LiBF4 in the polymer complex at 304 K.