An experimental apparatus for the methane and air mixture explosion with N-2/CO2 in a closed vessel was set up. A series of experiments have been performed to analyze the effects of N-2/CO2 on explosion strength, limiting oxygen concentration, flammability limits and explosion suppression. Results show that explosion strength decreases with the volume fraction of N-2/CO2 in the mixture. Limiting oxygen concentration decreases linearly with the volume fraction of N-2 in N-2/CO2 mixture. The flammability limits change linearly with the volume fraction of N-2/CO2 in the mixture. The higher the volume fraction of CO2 in N-2/CO2 mixture, the better the explosion suppression effect is. Based on experimental data, fitted equations and diagrams are made to predict methane flammability limits with N-2/CO2 under different volume fraction ratio of N-2 and CO2. The research results can be used as a reference for the inerting treatment design of methane explosion protection in process industries. (C) 2014 Elsevier Ltd. All rights reserved.