In general, the conductivity of polypyrrole (PPy) is reduced by addition of magnetic nanoparticles as the additives owing to insulating effect of magnetic nanoparticles. In this article, novel electromagnetic functionalized PPy composite nanostructures were prepared by a template-free method associated with gamma-Fe2O3 nano-needles as the hard templates in the presence of p-toluene-sulfonic acid (p-TSA) and FeCl3 center dot 6H(2)O as the dopant and oxidant, respectively. It was found that the molar ratio of gamma-Fe2O3 to pyrrole monomer represented by [gamma-Fe2O3]/[Py] ratio strongly affected the morphology and the conductivity of the gamma-Fe2O3/PPy composite nanostructures. A growth mechanism for the composite nanostructures was proposed based on the variance of the morphology with the [gamma-Fe2O3]/[Py] ratio. Compared with previously reported gamma-Fe2O3/PPy composites, the as-prepared novel composite nanostructures showed much higher conductivity (up to similar to 50 times higher). Moreover, the synthesized gamma-Fe2O3/PPy composite nanostructures displayed ferromagnetic behavior with a high coercive force. Explanations for these interesting observations were made in terms of the magnetic interaction between ferromagnetic gamma-Fe2O3 nano-needles and spin-polaron of PPy nanotubes. (C) 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 4446-4453, 2009