The topic of Diluted Combustion Technologies is reviewed from early developments some 10 ten years ago up to date, for the sake of “design and process engineers”. Recent efforts of the academic community to supply interpretation and quantitative modelling of the occurring phenomena are briefly described. Diluted combustion with high temperature reactants, in particular with gas firing, has been developed since a few years for industrial use exhibiting ultra-low NOx emissions and suitable properties for extremely high air preheating, and therefore substantial energy savings and process advantages. Successful applications to high temperature furnaces, mainly in the steel industry, are illustrated to show several advantages obtained from applying the new combustion technologies. This story is a good lesson based on conscious, scientific approach, backed by permanent R&TD efforts. These examples should be pursued vigorously if concrete measures to cope with the Kyoto engagements to combat air pollution are to be brought about in reality.