Abstract: A process and plant for improving the incineration of fuels, in order to reduce the production of noxious gases, particularly nitrogen oxides (NO.sub.X) and also to reduce the emission of dioxines and furans when incinerating solid or liquid wastes containing precursors of dioxines and furans. Air containing an excess of oxygen is used for incinerating the combustible materials. The amount of oxygen contained in the enriched air is preferably of about 30 to 35% with respect to the normal content of oxygen (23.19%). The plant comprises essentially at least one combustion chamber and an equipment for supplying air enriched with oxygen to said combustion chamber.