Carbon nanofilaments were grown on silicon substrates by using a novel catalytic method in an organic liquid hydrocarbon. Nonequilibrium catalytic deposition gave significantly pure carbon nanofilaments with very little soot within a few minutes in n-octane. Scanning electron microscope images indicate that the nanofilaments are grown perpendicular to the Si substrate surface. This very rapid and dense production of carbon nanofilaments can be attributed to the great difference of chemical potential between the substrate surface and reactant liquid.