This invention relates to a process for the decomposition of material selected from the group consisting of organic compounds, inorganic compounds, or combinations thereof to compounds which are environmentally acceptable, or are amenable to further degradation by conventional disposal systems to produce environmentally acceptable products, which process comprises: (a) conveying an aqueous solution or an aqueous slurry of material into a reaction zone capable of withstanding the temperatures and pressures of decomposition of the material; (b) contacting the material in the reaction zone with aqueous sodium carbonate as a reactant in an amount effective to decompose the material under hot water or supercritical water oxidation conditions of between about 300.degree. and 600.degree. C. and a pressure of between about 20 and 400 atmospheres for between 0.1 and 120 min, wherein the sodium carbonate at the reaction conditions is present at about 10% or less as a water soluble salt as compared to the solubility of the salt at ambient conditions, wherein the process occurs in the presence of a gaseous oxidant present in an amount of between about 0.1 and 50% by weight of the material; (c) producing about 99% or greater of the decomposition of the material, or 99% or greater conversion of the material to compounds which are environmentally acceptable or to compounds which are amendable to further degradation; and (d) optionally degrading further the compounds produced in step (c) by reaction to environmentally acceptable products. Preferably, the specific reactant is sodium carbonate and the oxidant is oxygen or air.