The melting behavior and dynamic mechancial properties of poly(vinylidene fluoride) (PVDF) in composites with polypyrrole (PPy) have been investigated using DSC/DTA and a Rheovibron viscoelastometer. Composites with varying percentages of PPy (5-50%) were synthesized using a solution-casting method with FeCl3 as the oxidant. It was observed that the melting point of PVDF increased as the percent of PPy was increased. A plot of tan delta vs. temperature showed the shift of the alpha relaxation peak to higher temperature. These results, together with our earlier studies on the basis of XRD and IR, indicate molecular interaction, an antiplasticization effect of PPy, and partial phase transformation of PVDF to phase I (beta form).