The MW plasma torch (2.45 GHz) in the mixture of CH4/H-2/Ar (42/430/1540 sccm) with added Fe(CO)(5) vapors was used for the synthesis of iron oxide nanoparticles and carbon nanotubes. The particles with well-defined facets consisting of Fe3O4 and gamma-Fe2O3 and self-assembled into long chains were produced at the power of 360 W. At higher power of 440-460W the deposit contained significant amount of multi-walled carbon nanotubes covered by iron oxide nanoparticles. The diameter of CNTs was 8-20 nm. The particles had Fe3O4 and/or alpha-Fe2O3 cores of spherical shape covered by a thin layer of carbon. (C) 2008 Elsevier B. V. All rights reserved.