An effective route of growing boron nitride nanotubes was developed. By reacting boron, silica and iron oxide catalysts supported on alumina, gas-phase reactants and liquid-phase catalyst could be generated in-situ. When ammonia was then introduced, boron nitride nanotubes could be formed by the reaction of boron oxide and ammonia inside the liquid-phase catalysts. The synthesized boron nitride nanotubes are highly-crystallized and multi-walled structures with 10-30 nm in diameter. The growth process was explained based on vapor-liquid-solid wire-like growth mechanism. (C) 2002 Published by Elsevier Science B.V.