A new approach to synthesizing carbon nanotubes (CNTs) using dispersed magnetic fluids, instead of conventional metallic catalyst nanoparticles of Ni, Co, or Fe, was proposed. A magnetic fluid of surfactant-coated magnetite nanoparticles has been successfully applied for CNT synthesis in chemical vapor deposition by a simple spin coating method. Using the method dense and aligned CNTs were successfully grown on Si substrates. We have found that mixing the magnetic fluid in polyvinyl alcohol renders a viscosity to the solution, secures uniform particles distribution without agglomeration, and controls the nanoparticle density on the substrate. This method of magnetic fluid dispersion offers a new inexpensive technology for synthesizing CNTs. (C) 2002 Published by Elsevier Science B.V.