To obtain the high dielectric constant and superparamagnetic composites for application in dielectric energy storage capacitors and other electromagnetic devices, the Fe3O4 nanoparticles have been embedded into polyvinylidene fluoride (PVDF) polymer. As expectation, a distinct percolation effect has been found in these composites, because of the good conductivity of Fe3O4 nanoparticles. The composites exhibit great increase of the dielectric constants and conductivities near the percolation threshold. The maximum of dielectric constant is up to 5240 at 100 Hz, which is the highest value reported to date among the PVDF based percolative composites. Meanwhile, the dielectric loss is controlled in the range of 02.2. These composites also exhibit superparamagnetic with the presence of Fe3O4 nanoparticles. The maximum of saturation magnetization is 30.8 emu/g. (C) 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012