High-quality single-walled carbon nanotubes (SWNTs) were obtained from are-produced soot using a three-step purification process consisting of soft oxidation, air oxidation, and a high-temperature vacuum treatment. Firstly an oxide layer was formed on the surface of the metal catalyst, which prevents the SWNTs from undergoing metal-assisted dissociation during the process. After the final step, about 20% of the weight of the initial raw soot remained and the final product contained less than 1% metal. Scanning electron microscopy, transmission electron microscopy and Raman spectroscopy were used to characterize the SVVNTs obtained. (C) 2002 Elsevier Science B.V. All rights reserved.