Hot-wire chemical vapor deposition (HWCVD) has been employed for the continuous gas-phase generation of both carbon multi-wall and single-wall nanotube (MWNT and SWNT) materials. Graphitic MWNTs were produced at a very high density at a synthesis temperature of similar to600 degreesC. SWNTs were deposited at a much lower density on a glass substrate held at 450 degreesC. SWNTs are typically observed in large bundles that are stabilized by tube-tube van der Waals' interactions. However, transmission electron microscopy analyses revealed only the presence of isolated SWNTs in these HWCVD-generated materials. (C) 2003 Elsevier Science B.V. All rights reserved.