The hydrogen fuel is considered to be an ideal source of energy, because its complete combustion generates no pollutants, only water vapor. Therefore, the hydrogen has been suggested as a clean fuel. A detailed kinetic mechanism for the combustion of hydrogen that comprises eight species (H2,O2,O,OH,H2O,H,HO2 and H2O2) and 20 elementary reactions, was reduced to two-step mechanism for nonpremixed flames involving four reactive species (H2,O2,H,H2O). We performed, for this mechanism, a numerical analysis of the equations, including the velocity, mixture fraction, mass fractions and temperature. To quantify the components of intermediary reactions, the mixture fraction is decomposed into three parts, each part directly related to the mass fraction of each species. The results compare favorably with data in the literature for a jet diffusion flame of 50/50% in volume of H2-N2. The main advantage of the strategy employed here is to decrease the work needed to solve the system of equations of the reactive flow.