Fe-filled thin-walled carbon nanotubes (CNTs) were synthesized by chemical vapor deposition. Dichlorobenzene/ferrocene solution was used both for carbon source as well as Fe source. Chlorine-contained precursor is in favor of the fabrication of thin-walled CNTs. The productive HCl in the reaction ambient could etch the CNT wall and growth front-end. Auger electron spectroscopy (AES) results indicated that the Cl atoms were almost entirely carried away by the carrier gas. Thermogravimetric analysis (TGA) showed that the filling rate of the Fe-filled thin-walled CNTs could be adjusted by controlling the flow rate of H-2. (C) 2008 Elsevier B.V. All rights reserved.