Different catalysts based on platinum and a silica, titania or mixed titania/silica support were studied in NO reduction reactions by CO and H-2 in the temperature range of 25-400 degrees C. The mixed oxide catalysts showed considerably lower onset temperatures in NO/CO reactions but this coincided with a maximum in N2O formation. In NO/H-2 reactions all titania containing catalysts produced more N2O than silica supported platinum at low temperatures but were more selective to N-2 at high temperatures.