The poly(3,4-ethylenedioxythiophene)/poly(styrene sulfonate)-Fe3O4 (PEDOT/PSS-Fe3O4) nanoparticles have been prepared by using polystyrene sulfonic sodium (NaPSS) as a dispersant and doped The characterization of nanocomposites was investigated by transmission electron microscope, X-ray diffraction, UV spectroscopy, electrochemical study, four-probe, thermogravimetric analysis and magnetic property measurement system. XRD revealed the presence of spinet phase of Fe3O4 and the average size was calculated to be about 12 rim. The conductivity of nanocomposites at room temperature is ex lent and it depends on the Fe3O4 content. The thermal stability of composites is outstanding. High saturation magnetization of 6.47 emu g(-1) (20 wt.% Fe3O4) was observed at 300 K. (C) 2009 Published by Elsevier