The majority of aerospace engines such as turboreactor and rocket engines work due to the process of combustion, which is also responsible for the formation of harmful and pollutants chemical species in the environment. The progress in engine technology asks constructors to respect the environmental regulations; this is required to develop ecological and cleaner engines. Our investigation was based on a configuration of cylindrical combustion chamber similar to the turboreactor, using the injection of methane and air with different inlet velocity, in order to calculate the temperature field and estimate the mass fraction of carbon monoxide (CO) at different region of the burner, using the solution of aerothermochemistry equations. The validation is based on experimental data of C.P. David (Sanford-USA. 2001).