The silicon nanowires (SiNWs) in this research were synthesized on silicon substrates via a catalytic reaction under N-2 annosphere by the thermal chemical vapor deposition system. Nickel catalyst was deposited on the silicon substrates by electroless nickel plating technique. It was found that the Ni content was increased from 0.31 wt.% (30 s, 75 nm) to 15.52 wt.% (300 s, 370 nm) from the energy dispersive X-ray spectroscopy analysis. It was also shown that the sizes of the Si-Ni alloy droplets and the growth density of SiNWs were both increased as the thickness of the electroless plating layer increased. It was concluded that the diameters, lengths and growth densities of SiNWs could be controlled by the Ni content of the electroless plating layer on the silicon substrate. (c) 2006 Elsevier B.V All rights reserved.