What is "hypoiodous acid"

n. (context chemistry English) the simplest oxyacid of iodine, HIO; it is formed when iodine dissolves in water, or when higher oxyacids are reduced

Hypoiodous acid is the inorganic compound with the chemical formula HIO. It forms when an aqueous solution of iodine is treated with mercuric or silver salts. It rapidly decomposes by disproportionation:

Hypoiodous acid is a weak acid with a pK of about 11. The conjugate base is hypoiodite (IO). Salts of this anion can be prepared by treating I with alkali hydroxides. They rapidly disproportionate to form iodides and iodates.