Carbon nanofibers (CNFs) were prepared by passing a mixture of acetylene/H-2 or acetylene/N-2 over different Cu catalysts. The Soxhlet extracted CNFs were characterized by TEM, TGA and IR spectroscopy and revealed that the morphology, diameter distribution and crystallinity of the CNFs varied with gas atmosphere and Cu particle size. TEM images revealed that coiled CNFs were only produced from Cu/SiO2 grown in the presence of H-2. It is thus revealed that the CNFs produced by different Cu catalysts have different chemical and physical properties and that these properties correlate with catalyst particle size and the gas mixtures used. (C) 2013 Elsevier B.V. All rights reserved.