NO and N2O formation and destruction was studied in a laboratory-scale fluidized-bed combustor for a set of coals ranging from lignite to anthracite. For a given coal, the sum of fuel-N conversions to N2O and NO was found to be remarkably constant over a range of temperatures, although emission levels of individual species were strongly temperature-dependent (NO increases and N2O decreases with increasing temperature). A similar behavior was observed for the formation of NO and N2O during combustion of chars. This trade-off between N2O and NO emissions can be regarded as a constant conversion of fuel-bound nitrogen to N-2. The influence of NO addition on the formation of N2O and N-2 was investigated in packed-bed gasification experiments using char prepared from a bituminous coal. The inlet concentration of NO was at a level typical for fluidized-bed combustion. It was found that NO reduction on char surface was strongly enhanced in the presence of oxygen. The majority of the added NO was converted to N-2, but some N2O was also formed. The temperature-governed trade-off between emissions of NO and N2O, and the formation of N2O and N-2 from NO reduction, are qualitatively explained on the basis of known heterogeneous and homogeneous NO/N2O chemistry.