A simultaneous thermogravimetnc/differential thermal analyzer with a range from 20 to 1600°C was used to study the nitridation of Ti powder. The influences of powder morphology, initial oxygen and nitrogen content and the effects of heating rate and sample size were investigated. The sample size and heating rate played an important part in the ignition behavior. The Ti powder ignited much less readily in nitrogen than in oxygen: an order of magnitude larger sample size was required. It was found that the α & rarrtl; β transition of Ti at 882°C is a necessary condition for ignition in nitrogen, unlike the oxidation process, where ignition occurs below the transition temperature. The nitridation and oxidation behavior of Ti were compared and major differences were identified.