To enhance the explosion suppression effects of water mist, various potassium halide additives were tested in a confined vessel filled with a 10% mixture of methane/air. Air and CO2 (0.7 MPa) were used as driver gases. The results revealed that halide additives exhibit considerable suppression effects on explosion overpressure. A 30% KI mist decreased the explosion overpressure by 27.46% compared with the suppression by pure water mist under the same conditions. When CO2 is used as the driver gas, it will dissolve in water under high pressure. The synergistic effect of a CO2 solution with an effective additive afforded significant suppression. Under the same conditions, the overpressures suppressed by a mist of 30% KI + 0.7 MPa CO2 solution decreased by 3353% compared with those suppressed by pure water mist driven by air. The synergistic suppression effect is much better than that of a 0.7 MPa CO2 solution mist or 30% KI mist alone. The multicomponent additives can be considered when suppressing methane/air explosions with pressure-formed water mist. (C) 2019 The Chemical Industry and Engineering Society of China, and Chemical Industry Press Co., Ltd. All rights reserved.