A hypohalous acid is an oxyacid consisting of a hydroxyl group single-bonded to any halogen.
They can be formed by reacting the corresponding diatomic halogen molecule (F2, Cl2, Br2, I2) with water in the reaction: This also results in the corresponding hydrogen halide, which is also acidic.
Only hypofluorous acid has been isolated as a solid, and even it is explosive at room temperature.
[1] Hypochlorous acid cannot be prepared in anhydrous form.
[2] Hypobromous acid, hypoiodous acid, and their conjugate bases (hypobromite and hypoiodite) are also unstable, undergoing disproportionation reactions like and that result in the corresponding hydrogen halides/halide ions and halic acids/halates.