Carbothermal reduction and nitridation of ilmenite concentrates of different grades and synthetic rutile were studied in isothermal experiments in hydrogen – nitrogen gas atmosphere and pure nitrogen in a tube reactor. Concentrations of CO and CO₂ in the off gas were measured online using infrared gas analyser. The reaction products were analysed by X-ray diffraction. Iron oxides in ilmenite concentrates were reduced to metallic iron, and titanium oxides were converted to titanium oxycarbonitride. Reduction of ilmenite concentrates and synthetic rutile in hydrogen containing gas was significantly faster than in pure nitrogen. The rate of conversion of titania to titanium oxycarbonitride in the 50 vol% H₂-50 vol% N₂ gas mixture decreased with increasing grade of ilmenite concentrate. In nitrogen, reduction of synthetic rutile was faster than reduction of ilmenite concentrates.