1.4 wt% Pt-1.25 wt% Co-1.25 wt% Ce catalyst on MgO support was prepared using incipient to wetness impregnation technique and tested in a micro-reactor flow system for the low temperature preferential oxidation of CO in hydrogen rich streams. 100% CO conversion was achieved at 130 degrees C with a feed composition of 1.0% CO, 1.0% O-2, 60% H-2 and He as balance at a space velocity of 24,000 cm(3)/g-h. The addition of 25% CO2 did not affect the performance of the catalyst significantly, while 10% H2O in the feed decreased the activity. 100% CO conversion was obtained at 150 degrees C in the presence of 25% CO2 and 10% H2O in the feed.