Boron nitride nanotubes (BNNTs) are synthesized by the arc-jet plasma of high temperature (5000-20000 K), which is generated by a dc non-transferred plasma torch with a mixture of argon and nitrogen gas. The BNNTs produced by the thermal plasma process are resulted from the chemical reaction of a precursor material of hexagonal boron nitride with catalytic metal powders of Ni and Y introduced into the hot arc-jet plasma flame, which is ejected inside the cylindrical carbon reactor. The synthesized materials are evaluated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and electron energy loss spectroscopy (EELS). These material analyses reveal that multi-walled nanotubes including single- and double-walled ones with high crystallinity are synthesized in quantity, and that the diameter of nanotubes is estimated in the range of 3-10 run. (c) 2005 Elsevier B.V. All rights reserved.