Facile synthesis of carbon nanotubes in large quantity can be accomplished by direct thermal decomposition of ethanol in a stainless steel reaction chamber under high pressure. Raman and thermogravimetric data indicate that the as-synthesized carbon nanotubes are of high quality, with the prepared samples exhibiting low amorphous carbon content. TEM measurements confirm the formation of carbon nanotubes of several morphologies for the high-pressure synthesis. At pressures near atmospheric, however, very limited morphologies and yields for the nanotubes result. A mechanism involving catalytic site formation as a result of temperature dependent surface roughening is consistent with our observations. (c) 2005 Elsevier B.V. All rights reserved.