Thermal analysis of non-isothermal and isothermal oxidation of the carbonitride solid solution TaC1-xNx powder (x = 0-1.0 with variation of every 0.2) was performed using simultaneous TG-DTA-MS technique. Sintered TaC1-xNx bodies were prepared by spark plasma sintering of powder mixtures of TaC and TaN at 1800 degreesC. The crushed powder was oxidized non-isothermally by heating to 1000 degreesC or isothermally at 700-800 degreesC in a flowing mixed gas of Ar and O-2 (pO(2) = 20 kPa). The dependency of the oxidation of TaC1-xNx on the composition x was investigated from the standpoint of initiation temperature, completion temperature, and maximum rate. It was suggested that the oxidation kinetics are represented by either a diffusion-limited rate equation or a first-order reaction rate equation, depending on the composition and temperature. DTA-MS analysis in the very early stage of oxidation showed that N-2 gas evolves in advance Of CO2 with the respective exothermal effect. (C) 2004 Elsevier B.V. All rights reserved.