There are many routes to make nanoparticles and the resultant materials can have significantly different properties, depending on the route chosen to fabricate them like flame pyrolysis, electro-explosion, laser ablation, high-temperature evaporation and plasma synthesis. Gas phase synthesis is one among them. Gas phase synthesis technique essentially involves the controlled growth of a nanotube on a catalyst particle through the cracking of carbon-rich gases such as methane. The production of fullerenes and carbon nanotubes fall under gas-phase synthesis technique. It is possible to make low-purity nanotubes using electric discharge techniques, but this results in wide variations in materials within a batch. Most techniques are increasingly focused on the production of either single-or multi-walled nanotubes, with significant efforts going into increasing the purity and yields.