The successful growth of carbon filaments on two different precursors, i.e., the pristine sodium-montmorillonite (Na+ MMT), which undergoes reflux at 100 degrees C (r-MMT), and the Na+ MMT exchanged with Fe3+ ions (MMT(Fe)), was attained through chemical vapor deposition (CVD). The products obtained were characterized by X-ray diffraction, thermogravimetry, scanning electron microscopy, and transmission electron microscopy. Refluxing can make the Fe3+ ions in the octahedral layer of Na+ MMT migrate to the interlayer and exchange with Na+ ions. Furthermore, through calcination at 500 degrees C, the Fe3+ ions migrate again to the surface of the clay layer and form iron oxides, which can serve as precursors for the deposition of carbon. Although r-MMT contained less iron than the MMT(Fe), the ultimate yield of carbon components grown was almost the same, indicating that the iron species in r-MMT possess higher catalytic activity. However, on the surface of r-MMT, CVD hardly generated carbon nanotubes with a clear hollow structure but that those with a carbon fiber structure instead. (C) 2011 Elsevier B.V. All rights reserved.