The purpose of this paper is to prepare electrically conductive nanoparticles such as borides, mixture of nitrides and borides by induction thermal plasmas. Another purpose is to correlate the prepared particle composition with thermodynamic parameters. For B-N-M (M = Ti, Cr, V) system that has low Gibbs free energy of nitridation and boridation, boride and nitride nanoparticles were prepared. While B-N-M (M = Co, Fe, Mo) system that has high Gibbs free energy of nitridation, boride nanoparticles were mainly prepared. For B-N-M (M=Ta, Nb) system that has much higher nucleation temperature of metal than that of boron, nanoparticles of nitride with small fraction of boride were prepared, because these systems have different nucleation mechanism. The composition of prepared nanoparticles depends on the Gibbs free energy as well as the nucleation temperature. (C) 2003 Elsevier Science B.V. All rights reserved.