An efficient method that can be used to directly produce large areas of highly ordered isolated and relatively long carbon nanotubes (CNs) is developed. The method is based on the chemical vapor deposition procedure with a major improvement in the preparation of the substrate. The size and distribution of the CNs are determined by the catalyst particles: CNs can only grow on catalyst particles and have a diameter similar to them. The dispersion of catalyst particles on the substrate also plays a very important role in preparing pure CNs of small diameter and uniform thickness. CNs were synthesized inside the pores of nanoporous alumina membrane via polymerization of acrylonitrile.