Crystalline Si3N4/amorphous SiO2 nanocables have been synthesized from silicon substrates and N-2 at 1250 degreesC without any catalyst. The morphology, composition profiles and photoluminescence of the nanocables have been studied. It has been demonstrated that an inner crystalline Si3N4 is formed whereas the outer SiO2 is amorphous. The nanocables are 90-110 nm in diameter and several micrometers in length, while the core-wires are 30-50 nm in diameter. Intense blue or near violet photoluminescence from these nanocables was observed. A tentative growth mechanism model for the crystalline Si3N4/amorphous SiO2 nanocables has been suggested and discussed. (C) 2003 Elsevier B.V. All rights reserved.