五氧化二砷为砷(+5)的氧化物，化学式As₂O₅。与三氧化二砷等其他砷化合物同样具有较高毒性。通常为带玻璃光泽的白色固体。

用于杀虫剂、除草剂、杀菌剂、木材防腐剂、金属粘合剂、印刷与染色等诸多用途。

Arsenic pentoxide is the inorganic compound with the formula As₂O₅. This glassy, white, deliquescent solid is relatively unstable, consistent with the rarity of the As(V) oxidation state. More common, and far more important commercially, is arsenic(III) oxide (As₂O₃). All arsenic compounds are highly toxic and thus find only limited commercial applications.