Cobalt molybdenum nitride (Co3Mo3N) and molybdenum nitride (Mo2N) were investigated for the catalytic reduction of NO with H-2. The latter deactivated rapidly with time on stream, whereas the former remained active and stable over a test period of 30 h. The results of X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and H-2-temprature-programmed reduction (H-2-TPR) characterization indicated that the deactivation of Mo2N was due to the bulk oxidation of Mo2N toMoO(2). As for the Co3Mo3N catalyst, despite partial decomposition into Mo2N and Co, it remained resistant to oxidation. The results suggest that compared to the monometallic nitride, the bimetallic one is more suitable for NO reduction with H-2.