Ferrocene was dissolved in alcohol and such solution was used as the catalyst and carbon sources for the first time for producing single-walled carbon nanotubes (SWCNTs). This is different from the previous studies in which the catalyst was supported on either zeolite or a substrate when alcohol was used as the carbon source. Because of the use of a floating catalyst, SWCNTs could be produced continuously. Because of the use of alcohol, the formation of impurities, such as amorphous carbon, multi-walled carbon nanotubes and carbon nanoparticles were suppressed. Due to the simplicity of the present technique, it may be suitable for scale-up for mass production. (c) 2005 Elsevier B.V. All rights reserved.