A method and apparatus for conducting supercritical wet oxidation reactions wherein any precipitated solids do not contact the solid side walls of the containment vessel so as to prevent any of these precipitated solids from adhering to or corrode the vessel walls is provided. To do this, a controlled, continuous flow of clean fluid, preferably under supercritical conditions, is introduced to the process so as to form a film-like, clean fluid surface between the physical containment vessel walls and the supercritical wet oxidation reactants.