The burning velocity of premixed carbon monoxide-nitrous oxide flames (background water levels of 5 to 15 ppm) has been determined experimentally for a range of fuel-oxidizer equivalence ratio phi from 0.6 to 3.0, with added nitrogen up to a mole fraction of X-N2 = 0.25, and with hydrogen added up to X-H2 = 0.005. Numerical modeling of the flames based on a recently developed kinetic mechanism predicts the burning velocity reasonably well, and indicates that the direct reaction of CO with N2O is the most important reaction for CO and N2O consumption for values of X-H2 less than or equal to 0.0014. The calculations show that a background H-2 level of 10 ppm increases the burning velocity by only about 1% compared to the bone-dry case. Addition of iron pentacarbonyl, Fe(CO)(5), a powerful flame inhibitor in hydrocarbon-air flames, increases the burning velocity of the CO-N2O flames significantly. The promotion is believed to be due to the iron-catalyzed gas-phase reaction of N2O with CO, via N2O + M = N-2 + MO and CO + MO = CO2 + M, where M is Fe, FeO, or FeOH. Published by Elsevier Science Inc.