Abstract: This study investigated the performance of three kinds of transition metal ions (Mn2+, Cu2+, and Zn2+) modified zeolite 4A particles in suppressing methane/air coflowing flames on cup burner. Ion-exchange method was employed to incorporate different amount of transition metal ions into parent zeolite 4A. Fire suppression effectiveness of zeolites containing varied molar percentage of metal ions was tested by cup-burner method. Results showed that transition metal ions modified zeolites outperformed the parent zeolite 4A with a ranking order of Mn2+ >, Cu2+ >, Zn2+. Performance of the zeolite particles was affected by the percentage of transition ions loaded, which dominated the number of active sites and Brunauer-Emmett-Teller surface area of the particles. Increasing molar percentage of metal ions loading increased the capacity to scavenge flame radicals, but decreased Brunauer-Emmett-Teller surface area of the particles. There existed an optimized molar percentage of transition metal ions loading where the best fire-suppressing effectiveness was exhibited.