<p>This study systematically examined the stability of Ti(C,N) hard phases and denitrification during sintering of Ti(C,N)-based cermets using Ti(C_1−<i>x</i>,N_x) solid solutions with different N/C ratios. The stability of the solid solutions depended on their composition and sintering atmosphere, with the final sintered bodies divided into four distinct phase regions based on the N/C ratio and the nitrogen partial pressure. The denitrification rate of the solid solutions increased with temperature but decreased with higher N/C ratios. When used as hard phases in cermets, the denitrification rate of the sintered body increased as the N/C ratio decreased, without compromising density. An N/C ratio of 4/6 produced a more uniform microstructure with a complete and moderately thick rim phase. Denitrification persisted throughout sintering, peaking between 1240&#xa0;°C and 1400&#xa0;°C and being lowest during cooling. The process involved three sequential mechanisms: oxidation-induced, decomposition-induced, and dissolution-induced denitrification, dominating at low, intermediate, and high temperatures, respectively.</p>