One source of pollution in the combustion of fossil fuels is the formation of nitrogen oxides. Their production is strictly bound to the presence of molecular nitrogen in the combustion air and to the so-called fuel nitrogen, that is, the N chemically bound to the fuel. Thermal NO x formation, which is the most important source of nitrogen oxides in high-temperature combustion processes, can be limited and controlled by the relatively new "mild" technology, also called "flameless" combustion. However, if a fuel containing some nitrogen is used, other ways of NO x production become important. The aim of this study was to investigate the possibility of reducing fuel-NO x emissions using a laboratory-scale burner for mild combustion. Two selective noncatalytic reduction technologies, namely a reburning-like and thermal DeNO x -like have been coupled with mild combustion to further reduce NO x formation and the experimental results have been discussed using detailed kinetic calculations.