The　early　formation　of　phosphate　oxide　formed　on　316　stainless　steel　(316　SS),　nickel-based　Alloy　625,　and　titanium　alloy　TA8　exposed　in　supercritical　water　(400　degrees　C,　25　MPa)　containing　phosphate,　chloride,　and　oxygen　was　investigated.　Phosphate　corrosion　products　of　austenitic　stainless　steel　displayed　the　severest　spallation.　Stable　phosphates　oxide　films　were　inclined　to　form　on　Alloy　625.　TiO2　and　Ti2O3　are　the　two　main　components　of　oxide　films　on　TA8.　There　is　a　strong　synergistic　effect　between　phosphates,　oxygen,　and　supercritical　water,　leading　to　severe　corrosion.　The　corrosion　behavior　of　the　three　alloys　at　the　top　and　bottom　of　the　reaction　tube　was　compared.　Both　at　the　top　of　the　reaction　tube　and　at　the　bottom　of　the　reaction　tube,　TA8　showed　an　increase　in　mass.　316　SS　and　alloy　625　showed　mass　gain　at　the　top　and　mass　loss　at　the　bottom.　The　alloys＇　detailed　molten　corrosion　mechanism　after　exposure　to　supercritical　water　is　discussed.