Nitrogen-doped carbon nanotubes are synthesized by the pyrolysis of CH3CN with/without H-2 over MgO supported Fe catalysts at 850 degreesC in argon flow. In both cases nitrogen is introduced to dope the product with quite different amount. TG analysis, Raman spectroscopy, SEM and TEM results showed that the introduction of H-2 is favorable for the formation of multi-walled nanotubes (MWNTs) containing less nitrogen. (C) 2003 Elsevier B.V. All rights reserved.