MoVTeNbO complex metal oxide catalyst is active and selective in the ammoxidation of propane to acrylonitrile. In order to clarify the redox process of this catalyst, the bulk structure and catalytic behavior were investigated by a pulse technique, in which the reactivity of propane, ammonia and lattice oxygen of this catalyst was observed. The mixture of propane and ammonia was pulsed onto the MoVTeNbO catalyst in a helium stream at a temperature of 420 degrees C in the range of 1-120 pulses and was selectively converted to acrylonitrile, while the lattice oxygen on the surface of the catalyst was abundant. And then the conversion of propane has decreased greatly as the pulse number increases to 12. The consumption of lattice oxygen to the whole of surface lattice oxygen was estimated to be 33%. On the other hand, ammonia was still converted after 12 pulses. After 120 pulses, the bulk structure was collapsed by the consumption of lattice oxygen. However, it revived again by exposing to the gaseous oxygen. This behavior indicates that only the lattice oxygen of the surface of the catalyst mainly takes part in propane ammoxidation. (C) 2007 Elsevier Ltd. All rights reserved.