The research focused on the conclusion of a mathematical model to determine the proportion of nitrogen oxides emitted from the internal combustion engine based on the equations of chemical interaction of direct and reverse the conventional fuel with the use of many of the correction coefficients, as well as the possibility of developing this model. Search to find out the concentration of nitrogen oxides NO changes resulting from the combustion of fuel in internal combustion engines that run on diesel fuel and gasoline adopted, during work time, and then transform this relationship to calculate the ratio of the concentrations according to the angle of rotation of the engine crankshaft.