Two successive generations of multiwalled carbon nanotubes (MWCNT/1 and MWCNT/2) have been produced by a unique CVD procedure using fibers of a commercial carbon paper as support. MWCNTs/1 have diameters comprised between 30 and 50 nm and are about 10 mum long. They are firmly attached to the carbon paper support. MWCNTs/2 have diameters of 10-20 nm and lengths of several 100 nm. They are grown on MWCNTs/1 and have a density of about 40 nanotubes per micrometer length of MWCNTs/1. This hierarchical nanostructure may find application as support for electrochemical catalysts, especially those used in fuel cells. (C) 2004 Elsevier B.V. All rights reserved.