Magnetite (Fe3O4) nanoparticles were prepared via polyol method by using FeCl2 as only source of iron. As-prepared samples were characterized by powder X-ray diffractometer (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (Fr-IR), thermal gravimetric analyzer (TGA) and vibrating sample magnetometer (VSM). Crystalline phase was identified as Fe3O4 and the crystallite sizes were calculated as 19.1 +/- 1.1 and 22 +/- 1.3 nm for uncalcinated and calcinated products from X-ray line profile fitting. The capping of heptanoic acid around Fe3O4 nanoparticles was confirmed by FT-IR spectroscopy, the interaction being via bridging oxygen's of the carboxylate and the nanoparticle surface and also by TG analysis. VSM measurements showed that both samples exhibited typical superparamagnetic behavior at room temperature with different Ms values. The epsilon' decreases with increasing frequency for both composites and permeability has almost same values for all temperatures at higher frequencies. As synthesized and calcinated samples conductivity increase linearly with the temperature. (C) 2012 Elsevier Ltd. All rights reserved.