The　phenomenon　of　spontaneous　combustion　during　the　release　of　high-pressure　H2　is　critical　to　the　safe　storage　and　transportation.　Besides　physical　methods　to　suppress　self-ignition,　the　approach　of　mixing　low-reactivity　gases　has　gained　increasing　attention.　Previous　work　has　mainly　focused　on　the　flow,　physical　heating　effects,　and　boundary　conditions　of　self-ignition　in　mixed　gases,　while　the　intrinsic　chemical　reaction　mechanisms　of　spontaneous　combustion　remain　underexplored.　To　clear　this　issue,　this　work　uses　the　ReaxFF　MD　simulation　method　to　study　the　spontaneous　combustion　process　of　H2/CO　and　H2/CH4　mixtures　with　various　concentrations.　The　results　indicate　that:　(1)　in　pure　H2,　H2/CO,　and　H2/CH4　systems,　the　primary　initial　reaction　mechanism　is　H2+O2[dbnd]HO2+H.　Additionally,　in　some　mixed　systems,　CO　+　O2[dbnd]CO2+O　and　CH4+O2[dbnd]CH3+HO2　may　also　serve　as　initial　reaction　mechanisms.　(2)　Under　fuel-lean　combustion　conditions,　the　RIDTs　of　the　systems　decrease,　supporting　the　viewpoint　that　self-ignition　typically　occurs　first　in　fuel-lean　regions.　The　addition　of　CO　and　CH4　increases　the　RIDTs,　which　helps　inhibit　the　development　of　self-ignition.　(3)　In　H2-rich　environments,　CO　combusts　to　CO2　through　the　formation　of　HOCO,　while　CH4　undergoes　dehydrogenation　and　oxidation　processes　through　intermediates　such　as　CH3,　CH3O,　and　HCHO,　leading　to　the　formation　of　CO　and　CO2.　The　combustion　of　H2　is　also　influenced　by　these　processes.　(4)　The　addition　of　CO　and　CH4　increases　the　activation　energy　of　H2　combustion,　raising　the　reaction　energy　barrier　that　must　be　overcome　for　spontaneous　combustion.　This　effectively　helps　to　suppress　the　occurrence　and　development　of　self-ignition　during　the　release　of　high-pressure　gases.　©　2024　Hydrogen　Energy　Publications　LLC