This numerical study concerns the effect of CO2 addition to CH4 on aromatic chemistry. In the absence of any thermodynamical effects, purely kinetic factors cause increases in the amount of carbon dioxide to decrease benzene mole fraction. The reaction H+CO2⇌OH+COH+CO2⇌OH+CO proved very important. Simulations under adiabatic conditions shows that raising the concentration of CO2 leads to an increase in A1 mole fractions. This is caused by CO2 addition making the combustion less efficient, so that both the temperatures and the concentrations of the OH radical are lower than for pure methane. We also discovered that the CO2 kinetics reduces the amount of benzene under isothermal conditions whereas it increases it under adiabatic conditions. Finally, we found that CO2 addition to benzene has negligible kinetic effects on aromatic hydrocarbons, radicals and even CO. Overall, our study shows that the kinetic effects of carbon dioxide in biogas can be highly complex, non-linear and counter-intuitive.