Multiwalled carbon nanotubes (MWCNTs) were synthesized in a catalytic reaction using CaCO3 as catalyst support. Impregnated with conventional catalysts CaCO3 enabled the production of MWCNTs in a fixed-bed flow reactor at relatively low reaction temperature. The purification was performed in one step: both metallic particles and catalyst support were dissolved in a diluted acid. Hence, disadvantages, namely multi-step processes and hazardous chemicals, were avoided. A further advantage of CaCO3 support is efficient and stable growth of MWCNTs. First results obtained in our new rotary-tube oven indicated high quality and pure MWCNTs with a yield of 100 g/day by this method. (C) 2003 Elsevier B.V. All rights reserved.