The production of titanium nitride by direct reaction of nitrogen and titanium oxide requires unrealistic conditions such as a high nitrogen partial pressure and quite low oxygen partial pressure. In contrast, titanium nitride can be prepared experimentally by carbonitrization with commercial grade nitrogen gas. However, because carbonitrization is a gas-solid reaction, a high reaction rate is not expected. I carried out a kinetic investigation into the carbonitrization reaction to clarify the titanium nitride formation mechanism. To achieve this, I used simultaneous thermal gravimetric and differential thermal analysis (TG-DTA). The ratio of carbonitrization to other reactions, such as the combustion of carbon, was determined using reaction enthalpies from a thermodynamic literature. Using kinetic analysis, the net carbonitrization reaction was found to comprise a series of consecutive reactions, and the order of the reaction was determined to be n = 0.1 to 0.5. That is, the reaction of titanium nitride formation is controlled by diffusion processes, as indicated by the dimension of “n,” and is dependent on the previous combustion process, the combustion of carbon.