Abstract: One-dimensional carbon nanomaterials involving carbon nanotubes (CNTs) and novel solid-cored carbon nanofibers (CNFs) were synthesized from flames by using methanol, ethanol and liquefied petroleum gas as fuels, and low carbon mild steel and Ni-contained alloys as substrates. The nanomaterials were characterized by field emission high resolution scanning electron microscopy, transmission electron microscopy and laser Raman spectroscopy. It was found that the morphologies of the nanomaterials were determined mainly by the substrates. A substrate containing Fe tended to produce the solid-cored CNFs on low carbon mild steel substrates, whereas a substrate containing Ni tended to produce hollow-cored CNTs. This was because Fe has a stronger affinity for carbon than Ni. The fuels also influenced the morphologies of the nanomaterials due to the differences in carbon content and combustion energy, etc.