Preparation of diamond films by hot filament chemical vapor deposition (HF-CVD) and nucleation of carbon nanotubes on diamond films were investigated. The optimum parameters for preparing diamond film were explored. Diamond films of high quality were deposited on silicon substrates seeded with carbon nanotubes as nucleation precursors. Diamond grains grew essentially perfectly with no congregation occurring during long depositions. The effect of the quality of the carbon nanotubes on the character of the deposited diamond are discussed. (C) 2002 Elsevier Science B.V. All rights reserved.