This paper looks at reburning (in-furnace NO x removal process) which can be a useful ecologically solid waste incineration method. Natural gas reburning fuel is added above the main combustion zone to form a fuel-rich zone where NO is partially reduced to N and to other nitrogenous species such as HCN and NH 3 . After this zone, additional air is supplied to the burnout zone to ensure complete combustion, oxidizing any remaining fuel such as CO and H. NO x reduction in simulated exhaust gas was experimentally and numerically studied to clarify the fundamental reburning reactions. The calculated and experimental results agreed very well and it was shown that N 2 O production as an intermediate product was needed to convert nitrogenous species to N in an oxidizing atmosphere for which two temperature regions were required: 700-800°C for N 2 O production, and 1000°C for N 2 O decomposition.