Titanium oxycarbonitride was produced by carbothermal nitridation of rutile. Mixtures consisting of titania and graphite with different carbon to titanium dioxide molar ratios were pressed into pellets and subsequently heated under nitrogen atmosphere at 1450 degrees C. Titanium oxycarbonitride was chlorinated in a horizontal tube furnace using chlorine and Cl-2-N-2 gas mixture. Effects of furnace temperature, chlorine partial pressure, gas flow rate, and particle size on the rate and extent of chlorination were examined. The chlorination was ignited at 150-200 degrees C. Chlorine partial pressure in Cl-2-N-2 gas mixture, gas flow rate, and particle size affected the chlorination rate, while the effect of particle size was insignificant. Extent of chlorination of titanium oxycarbonitride produced with carbon-to-titania molar ratio at 2.5 was close to 100% after 40 min of reaction.