the present invention provides a process for the manufacture of carbon nanostructures , the carbon nanostructures being selected from carbon nanotubes and carbon nano - onions . the method comprises the steps of injecting a carbon - containing gas into a plasma flame generated from a plasma forming gas to provide atomic carbon , which in the presence of in situ generated nanometer sized metal catalyst particles that act as nucleation points for growth of carbon nanostructures , produce the carbon nanostructures , and collecting the carbon nanostructures .