Iron and iron oxide-filled carbon nanotubes (CNT) have been produced by an one-step route based on the pyrolysis of ferrocene or a ferrocene-Fe-3(CO)(12) mixture in a poor oxygen-containing atmosphere, using the reactor quartz tube wall and porous Vycor glass (PVG) as substrate. XRD, TEM and HRTEM studies reveal the presence of CNTs, bucky-onions and carbon nanopolyhedra, filled with alpha-Fe, Fe2O3 and Fe3O4. The carbon formed inside the pores of PVG was extracted from the glassy matrix yielding thin and short CNTs or structures resembling carbon foam. The preparative method opens up new avenues for iron oxide filled-CNT and bucky-onions synthesis. (C) 2003 Elsevier B.V. All rights reserved.