The N-doped carbon nanotubes (CNx) were prepared by catalytic chemical vapor deposition of ethylenediamine with a series of Mg/Fe layered double hydroxides (LDHs) as catalyst precursors. The catalytic actived Fe particles were obtained by calcination of LDHs containing Fe3+ ions followed by reduction. The purification of CNx was carried out using a diluted nitric acid. The obtained products were characterized by X-ray diffraction, inductively coupled plasma spectrum, transmission electron microscope, X-ray photoelectron spectroscopy and Raman spectroscopy. The growth temperature has a distinct effect on the morphology and structure of CNx. Enhancing the growth temperature from 550 degrees C to 750 degrees C, the morphology of CNx changes from straight to bamboo-like and to bell-like, whereas the N-doped level decreases from 8.8 to 5.7 at.%. The content of Fe in precursors has little effect on the morphology of CNx, but it affects the N-doped level and structure. These results indicate that the morphology and structure of CNx are related to the synthetic parameters, like the growth temperature and composition of catalyst. Crown Copyright (C) 2010 Published by Elsevier B.V. All rights reserved.