The low reaction temperature for synthesis of carbon nanotubes (CNTs) with high quality was investigated by Ni/MgO catalytic decomposition of CH4 using a home-designed micro-fluidized bed reactor. It was found that the low and mild temperature at 500 similar to 550 degrees C would bring the dynamic equilibrium between the rate of CH4 decomposition and the rate of carbon diffusion over Ni catalyst for continuous precipitation of CNTs in the micro-fluidized bed condition. The CNTs synthesized at the corresponding conditions exhibited high quality with relatively small and mean outer diameter, less defect, and high purity. (C) 2013 Elsevier B.V. All rights reserved.