A single-step complex decomposition method for the synthesis of bulk and alumina-supported gamma-Mo2N catalysts is described. The complex precursor (HMT)(2)(NH4)(4)Mo7O24 center dot 2H(2)O (HMT: hexamethylenetetramine) is converted to gamma-Mo2N under a flow of Ar in a temperature range of 823-1023 K. Furthermore, decomposition of the precursor in a NH3 flow forms gamma-Mo2N in a temperature range of 723-923 K. Compared with direct decomposition of the precursor in Ar, the reaction in NH3 shows obvious advantages that the nitride forms at a lower temperature. In addition, alumina-supported gamma-Mo2N catalysts with different nitride loadings can be prepared from the alumina-supported complex precursor in the At or NH3 flow. The resultant catalysts exhibit good dibenzothiophene HDS activities, which are similar to the gamma-Mo2N/gamma-Al2O3 prepared by traditional TPR method. The catalyst prepared by decomposition in an At flow exhibits highest activity. It proves that such a single-step complex decomposition method possesses the potential to be a general route for the preparation of molybdenum nitride catalysts. (c) 2007 Elsevier B.V. All rights reserved.