A mathematical model of the transpiring wall reactor (TWR) for supercritical. water oxidation (SCWO) of the University of Valladolid, Spain, has been developed, and the results calculated have been compared to experimental data of the reactor. This model divides the reactor into three main areas of different flow patterns: mixer (plug flow (PF)), upper part (CSTR), and cooling zone (PF). The comparisons of the calculated temperature profile to the experimental one and the calculated total organic carbon (TOC) removal to the experimental one are favorable. Thus, a theoretical study of the main operation parameters has been carried out. It is convenient working with the reactor using a feed of 16.5 kg/h, a transpiring flow relation of 0.5, a transpiring flow temperature of 200 degrees C an air inlet temperature of 300 T, and an isopropyl alcohol (IPA) concentration of 8% ww. Working with higher concentrations of IPA is possible to reduce feed and transpiring flow temperature and to work without preheating air and transpiring flow, obtaining TOC removals near 100%.