A system and method using superheated steam optionally augmented by oxygen for the reduction of nitrogen oxides present for reducing nitrogen oxides present in a wide variety of organic compounds. The system includes a single reaction vessel, or optionally, multiple reaction vessels in operational communication. Reduction takes place quickly when a steam/oxygen mixture is injected into the reaction vessel or vessels. Reducing additives are metered into the reaction vessel or vessels and/or provide energy input to reduce nitrates to nitrogen. The oxygen, when used, allows for some oxidation of waste by-products and provides an additional offset for thermal requirements of operation.