The ammoxidation of propylene to acrylonitrile over Mo-Bi/alpha-Al2O3 catalyst was investigated in a bench-scale hot model riser reactor with 7 mm i.d. and 30 m in length. Propylene conversion and product yields were investigated under various operation conditions and the optimum conditions have been found for the new type reactor. The results show that the efficiency of catalyst is increased by four times and the yield of acrylonitrile is increased by 3% for type A catalyst and by 6.5% for type B catalyst in comparison with a commercial turbulent fluidized bed reactor. The yield of acrylonitrile can be further increased through staged air feeding strategy. (c) 2007 Elsevier B.V. All rights reserved.