Advanced thermodynamic model of a catalytic partial oxidation (CPOX) reactor was developed. The dynamics of the reactor were simulated using differential algebraic equations (DAEs). The aim of the project was to create a reliable and fast model that will be used for control purposes maximizing the hydrogen yield from the CPOX reaction. The composition of the output flow and species concentration is controlled by the input mass flows of fuel (Dodecane) and air. The state variables of the reactor considered in this model are temperature and total internal energy of the reactor. There are many options to customize the reactor model, from the geometry and materials used to build the reactor shell to different compositions of the gases fed to the reactor (fuel and air).