Carbon-nanofibres and carbon-nanotubes were grown in a vertical flow-reactor. Ferrocene was used as a catalyst and organic precursors like xylene, benzene and acetylene as carbon sources. Experiments were carried out in an argon and argon/hydrogen atmospheres. The experiments were performed at normal or reduced pressure and process temperatures ranged between 650 and 1070 o C. Layer deposition of carbon nanotubes/nanofibres were observed on the reactor wall and powders could be collected from the exhaust gas after the furnace. At low reaction temperatures and low ferrocene-concentrations the deposition of well-aligned homogeneous multiwall-carbon-nanotubes were found on the reactor wall. By increasing the temperature, and reducing the gas pressure, the nanotubes were grown together and high amounts of low-quality carbon-nanotube powder were collected from the exhausted gas. It could be shown that nanotubes only grew if hydrogen was added to the gas flow. The deposited layers and powders containing carbon-nanofibres and multiwall-nanotubes were observed by TEM.