Abstract: The invention relates to a system and method for the hydrothermal oxidation of water-insoluble organic residues. The plant comprises two independent liquid phase feed lines, namely an aqueous phase (1) and a non-water-soluble phase (9). The supercritical conditions in the entrance to the first reactor (10) enable a homogeneous phase to be obtained, in which there are no solubilization problems, thereby enabling the treatment of industrial residues that cannot be treated with standard systems. The inventive system comprises two reactor sections (14 and 18) such that it is possible to inject streams of hydrogen peroxide (11 and 15) in the connections between sections (13 and 17), in order to potentiate the oxidation reaction. The plant is equipped with a heat exchange system (5) in order to make use of the energy generated during the oxidation process, such that the plant operates in autothermal conditions.