This report will present a special form of combustion, called flameless oxidation. In contrast to the combustion within stabilized flames, temperature peaks can be avoided at flameless oxidation. For that reason, the thermal NO-formation is largely suppressed, even at very high air preheat temperatures. A brief summary of the present NOx-reducing techniques will be given. The illustration of flameless oxidation will cover the explanation of the basic principle, the presentation of calculated and measured data and the introduction of some application examples. The results are encouraging the assumption that NO-emissions from a wide range of combustion sources could be largely eliminated in the future. Use of burners, operated in flameless oxidation mode in continuous industrial furnaces have proven to be reliable and well accepted for the very uniform product quality by furnace people.