Electromagnetic interference shield materials which are multicomponent polymer nanocomposites consisting of insulating polymer matrix of poly (vinylidene fluoride-hexafluoropropylene) (PVdF-HFP), organic/inorganic salts, electron-conducting nanofillers (MWCNTs), and insulating superparamagnetic nanoparticles (Fe3O4), have been studied. It has been found that the introduction of the salts and nanofillers in PVdF-HFP not only improves the conducting nature and skin depth of the polymer nanocomposites but also keeps the composite films thermally stable up to similar to 200 degrees C. Changes in the surface morphology on addition of each individual constituent have been evidenced by scanning electron microscopy. The rheological study shows the plasticization effect of organic/inorganic salts as well as provides a good estimation of the polymer-particle interaction in the polymer nanocomposites. Furthermore, effect of organic/inorganic salts and interaction between the polymer and the fillers (MWCNTs and Fe3O4) has also been observed in differential scanning calorimetry in terms of lowering of glass transition temperature (leading to enhanced flexibility). The stress versus strain behavior has shown specific interactions among different constituents of the shield material.