A simple method to grow vertically aligned arrays of various forms of single-walled carbon nanotubes (V-SWNT) is reported. CO disproportionation on Co-Mo bimetallic catalysts has been used in the synthesis. Resonant Raman and transmission electron microscope (TEM) were employed to characterize the as-produced SWNTs, which display a high purity and very low concentration of other carbon forms. Combination of AFM and SEM gives evidence for the crucial role of the surface distribution of the bimetallic (Co/Mo) catalyst particles on the substrate during the growth of SWNT. A novel growth mechanism is discussed. (c) 2006 Elsevier B.V. All rights reserved.