The Effect of the presence of nitrogen and carbon dioxide in H2S acid gas stream is investigated. Concentrations of up to 30% of N-2 or CO2 in H2S stream have been examined. All cases were compared with the baseline case of 100% H2S acid gas stream. Temperature measurements showed that injection of CO2 or N-2 in the H2S stream decreases the flame temperature. However, injection of CO2 resulted in temperature increase downstream. Increase of carbon dioxide in the acid gas stream increased SO2 mole fraction in the byproducts. In addition, the increase of CO2 decreased the asymptotic value of H2S at downstream locations. Furthermore, the presence of CO2 decreased the amount of sulfur captured during the reaction process. This is attributed to increase in oxidizing medium in the reaction pool from the presence of carbon dioxide. The increase in oxygen fostered H2S combustion to form higher amounts of SO2. Subsequently, the amount of captured sulfur and asymptotic value of H2S decreased. On the other hand, the presence of nitrogen in the acid gas stream did not affect the reaction process significantly. Nitrogen acted as an inert gas on the reactants and did not affect the reaction chemistry. Published by Elsevier Ltd.