The supercritical wet air oxidation of olive oil mill wastewater has been carried out at 25.0 MPa of total pressure and temperatures in the range 380−500 °C. The process is well described by simple first-order kinetics with no dependence on the oxygen concentration when it is in excess. The apparent activation energy of the reaction has been found to have a value of 32.7 kJ mol-1 for chemical oxygen demand (COD) removal. Similar values have been calculated for other global parameters analyzed (total carbon, total organic carbon, etc.). The use of free-radical promoters enhances the efficiency of the treatment by lowering the activation energy of the process up to a value of 27.5 kJ mol-1 for COD elimination. Both promoted and nonpromoted oxidations mainly occur through total mineralization.