Abstract: An aqueous phase oxidization process for the oxidization of any nonoxidized feed material using a mixture of a feed material, an oxidizing acid, such as nitric acid; oxygen gas, water and preferably a stabilizing acid, such as sulfuric acid. The mixture is pressurized in a reactor and maintained at a temperature no greater than about 210.degree. C. Sufficient oxygen gas is added to increase the pressure beyond the pressure resulting from any gases formed during the oxidation process and to ensure that a substantial portion of reduction products of nitric acid formed during oxidation of the feed are substantially reoxidized to nitric acid.