The ignition of methane–air mixtures with additives of ClF5, ClF3, OF2, and H2O2 (additive content in the mixtures $$\le$$ 1%) is studied by numerical simulation. The ignition temperature of the mixtures is determined as a function of the initial pressure and additive content. It is shown that the introduction of the additives into the mixture leads to a significant decrease in the ignition temperature due to the acceleration of the formation of reactive species and intensification of the chain mechanism of the process. Of the additives considered, chlorine pentafluoride is the most effective additive, and hydrogen peroxide is the least effective one.