An　annual　production　of　about　500　million　tons　of　household　food　waste　(HFW)　has　been　documented,　resulting　in　significant　implications　for　human　health　and　the　environment　in　the　absence　of　appropriate　treatment.　The　anaerobic　fermentation　of　HFW　in　an　open　system　offers　the　potential　to　recover　high　value-added　products,　lactic　acid　(LA),　thereby　simultaneously　addressing　waste　treatment　and　enhancing　resource　recovery　efficiency.　Most　of　LA　fermentation　studies　have　been　conducted　under　mesophilic　and　thermophilic　conditions,　with　limited　research　on　the　production　of　LA　through　anaerobic　fermentation　under　hyperthermophilic　conditions.　This　study　aimed　to　produce　LA　through　anaerobic　fermentation　from　HFW　under　hyperthermophilic　conditions　(70　±　1　°C),　while　varying　pH　values　(5.0　±　0.1,　7.0　±　0.1,　and　9.0　±　0.1),　and　compare　the　results　with　LA　production　under　mesophilic　(35　±　1　°C)　and　thermophilic　(52　±　1　°C)　conditions.　The　findings　of　this　study　indicated　that　the　combination　of　hyperthermophilic　conditions　and　a　neutral　pH　(pH7_70)　yielded　the　highest　concentration　of　LA,　measuring　at　17.75　±　1.51　g/L.　The　mechanism　underlying　the　high　yield　of　LA　at　70　°C　was　elucidated　through　the　combined　analysis　of　organics　dissolution,　enzymes　activities,　and　16S　rRNA　microbiome　sequencing.　©　2024