The paper introduces the results of studying mechanism of interaction between a complex titanium-chromium ferroalloy and nitrogen under isothermal and non-isothermal conditions. The relevance of the research has both scientific and practical interest, as nitriding of a complex alloy containing several nitride-forming elements has not been investigated. The mechanism of nitride formation was studied under isothermal conditions in a resistance tube furnace under gaseous nitrogen in the temperature range of 700... 1200 °C for 15, 30, 60, 120 and 240 minutes. Nitriding under isothermal conditions was studied by differential scanning calorimetry using a synchronous thermal analyzer Netzsch STA 449 F3 Jupiter in the temperature range of 20...1500 °C under nitrogen. The process of nitride formation is found to be initiated due to reaction diffusion of nitrogen into chromium- and titanium-containing phases by solid phase mechanism to form nitrides of chromium (CrN) and titanium (TiN) with subsequent mutual dissolution and formation of a solid solution Cr0,5Ti0,5N.