Model supported palladium and palladium-molybdenum catalysts prepared from organometallic precursors and previously characterized by a variety of chemical and physical methods were examined by IR spectroscopy of NO chemisorption and tested for their activities as catalysts in the competitive NO + CO + O-2 reaction. The IR results reveal distinctive behavior of the catalyst made from a bimetallic precursor, and the activity results show that this catalyst is more selective for NO reduction than the other catalysts, but its stability is vulnerable to the reaction conditions. The high selectivity is attributed to Pd-Mo interactions, which are inferred to be stronger in the catalyst prepared from a bimetallic precursor than in catalysts prepared from monometallic precursors.