The high temperature combustion of the mixture Ta2O5 + 5 Mg has been investigated using a microthermocouple in the medium MgO and molten NaCl. The effect of varying the amounts of these two inorganic agents (MgO and NaCl) was examined. It was shown that using MgO as the reaction medium produces the complex oxide MgxTayOz as an impurity in the Ta powder, whereas unagglomerated single-phase powder (particle size of 20-90 nm) of Ta was formed in the presence of NaCl. The approximate mechanism for forming the final product is discussed. The distributions of temperature, the rate of heat generation and degree of conversion in the combustion wave of the mixture Ta2O5 + 5Mg + NaCl were measured. The sizes of the combustion zones and the kinetics of reaction were derived. (C) 2003 The Combustion Institute. All rights reserved.