A series of silica supported vanadium incorporated ammonium salts of 12-molybdophosphoric acid (AMPV) catalysts, with 5-25 wt% of active component were prepared. These catalysts were characterized by XRD, FTIR, BET-Surface Area, TGA/DTA and acidity by potentiometry techniques. The characterization data derived from XRD, FT-IR techniques reveal that the AMPV on silica support exists in the form of Keggin structure. These catalysts are studied for the vapor phase ammoxidation of 2-methyl pyrazine (MP) to cyanopyrazine (CP). The conversion of methyl pyrazine increased with increase in loading on silica showing a maximum value of conversion at 20 wt% AMPV loading. The ammoxidation activity of these catalysts with and without vanadium is studied and the vanadium incorporation led to substantial improvement in the cynopyrazine selectivity.