In our study we use a highly efficient and simple methodology based on wet chemistry to fill single-wall carbon nanotubes (SWCNTs) with iron, and thus create quantum wires in a bulk. The research shown is unique in that it is the first experimental single-wall carbon nanotubes that have iron continuously within their core for extended length scale. The resulting Fe-filled SWCNTs show ferromagnetic behavior even at room temperature, despite the very small diameter. The intercalation of metals within single-wall carbon nanotube structures is a significant step towards the realization of the potential applications using these materials. (c) 2006 Elsevier B.V. All rights reserved.