A new class of materials, M(I)-M(II)-O-N (where M(I), M(II) = V, Mo, W, and Nb), has been synthesized by nitriding bimetallic oxide precursors with ammonia gas via a temperature programmed reaction. The oxide precursors are prepared by conventional solid state reaction between two appropriate monometallic oxides. The synthesis of the oxynitrides involves passing NH3 gas over the oxide precursors at a flow rate of 6.80 x 10(2) mu mol s(-1) (1000 cm(3) min(-1)), and raising the temperature at a rate of 8.3 x 10(-2) K s(-1) (5 K min(-1)) to a final temperature which is held constant for a short period of time. The oxynitrides thus obtained are pyrophoric and need to be passivated before exposing them to air. All these new bimetallic oxynitrides have a face centered cubic (f.c.c.) metal arrangement and high values of surface area. Their surface activity is assessed from their ability to chemisorb CO.