The paper gives results of a study which investigated an unknown mechanism by which N2O is formed in coal flames, using both detailed kinetic modeling and plug-flow simulator experiments. The mechanism has considerable importance in determining the influence of common and advanced NOx control strategies on N2O. Significant N2O emissions have been observed from coal and oil burning power plants but not from industrial gas flames, even when they are doped with an equivalent amount of fuel nitrogen. Kinetic modeling suggests that net N20 is unlikely to form within flame zones because of its rapid removal by: N2O + H yields N2 + OH. Also, reduction of NO on coal char, or coal char oxidation, can be significant N2O sources only if the rates are many times their published values. However, both kinetic modeling and experiments show that, if HCN appears in the gas phase between 1150 and 1500 K, it will be partially converted to N2O. The source of HCN may be either direct devolatilization or a char gasification reaction. This suggests that the N2O which appears in coal flames may originate from the homogeneous reaction of devolatilized char nitrogen in the fuel-lean post-flame region. The kinetics indicate that the formation is principally through the reaction: NCO + NO yields N2O + CO.