Ammoxidation of 3-picoline to nicotinonitrile was investigated on antimony promoted vanadium phosphorus oxide (Sb-VPO) catalysts and antimony promoted alumina supported vanadium phosphorus oxide (Sb-VPO/Al2O3) catalyst under atmospheric pressure and at 400 0C. The catalysts were characterized by means of X-ray diffraction, electron spin resonance, infrared, scanning electron microscopy, differential thermal analysis, ammonia chemisorption and BET surface area methods. The catalytic activity is correlated well with the physicochemical characteristics of the catalyst. Higher activity is observed for Sb-VPO-1 catalyst having lower surface area, lower oxidation state of vanadium and higher surface acidity. In supported system presence of VPO in highly dispersed state along with AlSbO4 phase is responsible for higher activity and selectivity. A redox cycle between (V4+) and (V5+) species appears to be responsible for the ammoxidation activity of VPO catalyst.