Single-walled carbon nanotubes have been synthesized by the catalytic decomposition of both carbon monoxide and ethylene over a supported metal catalyst known to produce larger multi-walled nanotubes. Under certain conditions, there is no termination of nanotube growth, and production appears to be limited only by the diffusion of reactant gas through the product nanotube mat that covers the catalyst. The present invention concerns a catalyst-substrate system which promotes the growth of nanotubes that are predominantly single-walled tubes in a specific size range, rather than the large irregular-sized multi-walled carbon fibrils that are known to grow from supported catalysts. With development of the supported catalyst system to provide an effective means for production of single-wall nanotubes, and further development of the catalyst geometry to overcome the diffusion limitation, the present invention will allow bulk catalytic production of predominantly single-wall carbon nanotubes from metal catalysts located on a catalyst supporting surface.