The effect of the substrate on catalytic metal clusters in nucleation process of single-walled carbon nanotubes was studied by classical molecular dynamics (MD) simulation. The melting point of a nickel cluster increased with increasing catalyst-substrate interaction. During clustering process of carbon atoms via a nickel cluster on a substrate, a layered structure of fcc(111) was formed parallel to the substrate and a graphene was also generated parallel to the layer in case of strong catalyst-substrate interaction while the orientation of nickel cluster was not affected by the substrate in case of weak interaction. (c) 2007 Elsevier B.V. All rights reserved.