Zhundong　coal　(ZDC)　has　attracted　much　attention　due　to　its　high　alkali　metal　content　which　can　lead　to　a　series　of　problems　such　as　furnace　slagging　and　ash　fouling.　Supercritical　water　gasification　(SCWG)　become　a　better　choice　for　ZDC　coal　utilization　because　of　its　unique　chemical　and　physical　properties.　The　transformation　mechanism　of　alkali　metals　during　SCWG　process　was　different　from　conventional　ways　of　coal　utilization.　Systematic　research　about　it　could　hardly　be　found.　In　this　study,　ZDC　was　used　to　explore　sodium　transformation　mechanism　and　kinetics　during　supercritical　water　gasification　under　typical　conditions.　We　got　four　kinds　of　sodium　including　the　water-soluble　fraction　(L1),　the　carboxylic　matrix　-associated　fraction　(L2),　the　macromolecular　organic　group　associated　fraction　(L3),　and　the　inorganic　silicate　mineral　fraction　(L4)　through　sequential　extraction　method　after　SCWG.　A　reaction　pathway　of　sodium　transformation　in　supercritical　water　gasification　was　proposed.　A　quantitative　kinetic　model　for　describing　sodium　transformation　mechanism　was　developed.　Finally,　it　was　found　that,　L1　played　an　important　role　in　catalytic　process　and　mineral　in　coal　weaken　the　catalytic　process　by　combining　with　L1.　L2　and　L3　served　as　the　two　important　intermediate　products　in　the　coal　gasification,　which　explained　the　catalytic　mechanism　of　sodium.　L3　showed　better　reactivity.　Sodium　finally　tended　to　deposit　in　the　form　of　NaSiAlO4　(L4)　which　was　stable　and　environmentally　friendly.　All　of　these　could　provide　basis　for　high-efficiency　utilization　of　ZDC　and　the　design　of　a　reactor.　(C)　2017　Hydrogen　Energy　Publications　LLC.　Published　by　Elsevier　Ltd.　All　rights　reserved.