Abstract The reaction between tantalum and nitrogen at 800°–1300°C has been studied. The total reaction involves both dissolution of nitrogen in the tantalum metal and nitride formation. Nitrogen dissolution is the predominant part-process during initial stages of the reaction. Four different nitrides — TaN 0.05, Ta 2N, TaN 0.8–0.9, and TaN — are formed during the reaction. The relative amounts of these are dependent on experimental conditions. Below 1,000°C mainly Ta 2N is formed, while above this temperature TaN 0.8–0.9 and TaN are the main reaction products. TaN 0.05 are formed in trace amounts at the nitride/metal interface.