Platinum catalysts supported on noncrystalline TiO 2 -ZrO 2 binary oxides were found to be highly active for the selective NO reduction in a stream of NO (0.08vol.%)-H 2 (0.08-0.56vol.%)-O 2 (10vol.%) at low temperatures (<100 o C). The NO conversion to N 2 /N 2 O occurred at >0.08vol.% H 2 and the selectivity to N 2 increased with increasing H 2 concentration. In situ DRIFTS measurement suggested that the high selectivity in this temperature range is closely related to a stoichiometric reaction between H 2 and NO oxidatively adsorbed as nitrate (NO 3 - ). By comparison with the results from a parallel study of H 2 -O 2 combustion, we propose that almost all of H 2 reacted is consumed by the reduction of nitrate species, which covered the Pt surface to inhibit H 2 -O 2 combustion. The NO reduction activity was sensitive to the catalyst pretreatment; the catalyst reduced in H 2 allowed 89% NO conversion at 90 o C, whereas the catalyst treated in O 2 required 175 o C to attain the lower conversion of 50%. The effect of the pretreatment is closely related to the reactivity of nitrate adsorbates produced via different routes.