This article reports a simple self-assembly process for facile one-step synthesis of novel electromagnetic functionalized polypyrrole (PPy)/Fe3O4 composite nanotubes using p-toluenesulfonic acid (p-TSA) as the dopant and FeCl3 as the oxidant. The key trick of the present method is to use FeCl3 as the oxidant for both PPy and Fe3O4 in the same time to synthesize PPy/Fe3O4 composite nanotubes in one-step. This facile one-step method is much simpler than the conventional approach using the Fe3O4 nanoparticles as the additives. Compared to the similar composites synthesized using the conventional method, the as-prepared PPy-p-TSA/Fe3O4 composite nanotubes using the facile one-step self-assembly process show much higher room-temperature conductivity. Moreover, the composite nanotubes display interesting ferromagnetic behavior. The electrical properties of the PPy-p-TSA/Fe3O4 composite nanotubes are dominated by the amount of FeCl3 while their magnetic properties are controlled by the amount of FeCl2. (C) 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 320-326, 2010