Supercritical Water Oxidation (SCWO) is a high temperature and pressure process whose operating conditions are beyond the critical point of pure water (Tc=374°C and Pc=221bar), and is a powerful technology to treat wastewaters in a clean and effective manner. Moreover, the heat released during the oxidation reaction allows the recovery of energy and improves the efficiency of the process. In those cases where the reaction of high concentrated wastewaters generates a high temperature profile in a thermally insulating tubular reactor, a temperature control system is necessary to keep the operation within safety limits. With the aim of controlling the temperature along the reactor, both cooling water and oxidant split injectors have been installed in a 25kg/h pilot plant. Experimental tests have been carried out to compare the operation of the pilot plant before and after those two improvements. Intermittent water injections provide a quick and located cooling. Each injection reduces the temperature inside the reactor by around 20–40°C, and the frequency between injections depends on the exothermicity of reactions. When oxidant split is added in two injections, air in defect for the first injection (n ≈0.5) and in excess for the second one (n ≈1.2), the peak of temperature can also be smoothened and the development of the reaction can be controlled. In both cases, the temperature profile along the reactor is effectively controlled and the reaction remains within safe limits that allow a stable and reliable treatment of highly concentrated wastewaters.