The B4C nanowires can be easily fabricated by employing an activated carbon, boron and Ni(NO3)(2). whereas almost no B4C nanowires can be obtained if activated carbon is replaced by pure carbon. The analyses show that there are Si and Al impurities in the activated carbon, and both Si and Ni are critical to the growth of the B4C nanowires. Additionally, the yield of the B4C nanowires is greatly increased if the B4C nanowires are grown by the carbon nanotubes-confined method when Si is introduced. The mechanism of the Si enhanced growth of B4C nanowires is discussed. (C) 2009 Elsevier B.V. All rights reserved.