Technologies are presented for reducing corrosion M supercritical water gasification through seeded sacrificial metal particles. The metal panicles may be seeded into one or more material input streams through high pressure injection. Once distributed in the SCWG reactor, the metal particles may corrode preferentially to the metal SCWG reactor walls and convert into metal oxides that precipitate out above the supercritical point of water. The precipitated metal oxides may then be collected downstream of the SCWG reactor to be reprocessed back into seed metal at a smelter. The seeded metal particles may complete a process material cycle with limited net additional waste.