Thermogravimetry (TG) is found to be a simple process to see the effect of the experimental condition on the some properties of synthesized carbon nanotubes (CNTs). A comparative study of thermogravimetry (TG) and derivative thermogravimetry (DTG) curves of CNTs, prepared under different experimental conditions is useful to investigate the influence of synthesis strategy on the thermal stability, yield and the nature of crystallinity of the CNTs. Single step in DTG profile under air atmosphere and high degradation temperature of sample in a TG curve shows the good quality and high yield of the CNTs. The samples of CNTs are prepared by CCVD of acetylene over Fe/Co and Fe/N4o in ratio of 1: 1 by weight supported on aluminium isopropoxide (AIP) in the temperature range of 700-900 degrees C. The investigations from the TG curves help to optimize the experimental conditions for the synthesis of CNTs by CCVD method. (C) 2007 Elsevier B.V. All rights reserved.