Carbon nanofibers (CNFs) were prepared by the catalytic decomposition of ethylene over Ni/Y-zeolite at 550 degrees C, followed by catalyst removal with bydrofluoric acid. The demineralised CNFs were impregnated in an aqueous solution of Ni(II) nitrate. The CNF-supported Ni exhibited high catalytic activity in the CVD synthesis of CNFs, proving that the structured CNF support served to stabilize Ni activity. Results clearly indicated that careful control of temperature and H-2 content was important to achieve the desired product. Changing the total flow rate did not seem to alter the type of carbon deposited but did change the deposition rate. (c) 2006 Elsevier B.V. All rights reserved.