Methanol　was　introduced　as　an　auxiliary　fuel　during　supercritical　water　oxidation　of　typical　nitrogen-containing　compound　of　ammonia.　A　mechanism-based　kinetics　model　for　oxidation　of　methanol/ammonia　in　supercritical　water　was　developed,　which　involved　Real-Gas　model　for　reaction　species.　The　combination　of　experimental　data　analysis　and　reaction　kinetics　simulation　was　executed　to　examine　the　release　of　radicals　and　heat　with　reaction　time　for　methanol　with　different　concentration　ranges.　Furthermore,　the　synergy　mechanism　between　kinetic　and　thermal　effects　of　auxiliary　fuel　was　clarified,　in　order　to　achieve　enhanced　degradation　of　refractory　pollutants　under　appropriate　reaction　temperature.　It　was　observed　that　the　effective　time　ranges　for　radical　production　and　reaction　temperature　rise　for　methanol　at　the　concentration　order　of　magnitude　of　~100　mmol/L　overlapped.　And　the　kinetic　action　could　promote　the　chain　reactions　of　ammonia,　which　initiated　from　elementary　steps　with　low　activation　energy,　while　the　thermal　action　further　improved　reaction　rate　constants　of　these　initiation　steps,　achieving　synergy　between　the　two　effects　and　leading　to　the　promising　removal　of　ammonia　(99.24%)　at　moderate　temperature　of　540　°C.　Furthermore,　in　the　binary　reaction　system,　ammonia　could　enhance　combustion　of　hydrothermal　flame　under　adequate　supply　of　radicals　from　methanol,　otherwise　it　would　have　played　a　negative　effect.　©　2021　Elsevier　Ltd