Abstract: An organic waste decomposition system and method is described having two reaction vessels in tandem, each using superheated steam augmented by oxygen for decomposing a wide variety of organic compounds to reduce both mass and volume. Decomposition takes place quickly when a steam/oxygen mixture is injected into a fluidized bed of ceramic beads. The speed of the fluidizing gas mixture agitates the beads that then help to break up solid wastes, and the oxygen allows some oxidation to offset the thermal requirements of drying, pyrolysis, and steam reforming. Most of the pyrolysis takes place in the first stage, setting up the second stage for completion of pyrolysis and adjustment or gasification of the waste form using co-reactants to change the oxidation state of inorganics and using temperature to partition metallic wastes.