Currently, the interest in using alternative clean types of fuels has been extensively increased all over the world because of the global approach in reducing engine emissions and creating new sources of fuel for internal combustion engines. The hydrogen-methane blend is one of the alternative fuels which includes the benefits of both of the fuels compared to the traditional petrol/gasoline fuel.This paper addresses a two-zone quasi-dimensional model to investigate the performance of an SI engine which uses a mixture of methane and hydrogen. In this model, gases inside the cylinder are divided into two regions: burned and the unburned. The chemical reactions are supposed to be in equilibrium in each zone, but the extended Zedlovich mechanism is utilized to determine the amount of the NOx available in the exhaust gas. Also, CO concentration is determined by two steps kinematic reactions. The flame front is assumed to be a surface with no thickness in adiabatic flame temperature. To validate the model, the results are compared with the experimental data obtained from reference studies. The comparison approves the applicability of the model in predicting the performance of the engine. Meanwhile, the model is tested with different equivalence ratios of the hydrogen-methane blend, and performance parameters of the engine such as pressure variation, power, thermal efficiency, and emissions are consequently derived and discussed in terms of the equivalence ratio.