Novel catalysts are presented for synthesizing carbon nanofibers (CNF) from ethylene decomposition. The catalysts are derived from hydrotalcite (HT) precursors, which contain high amount of active metal species. The synthesis process has been studied and optimized as a function of various parameters such as hydrogen content, gas space velocity, temperature, and catalyst composition. It was found that the yield, nanostructure, and quality of the CNFs were greatly influenced by these process parameters. The aim of the present article is to report the optimized large scale (128 g per gram catalyst) synthesis process of high quality CNFs at relatively low temperatures (< 650 degrees C). (c) 2005 Elsevier B.V. All rights reserved.