Periodic acid, crystalline pure, is a strong oxidizing agent and belongs to the periodates. It is the highest oxidation state of iodine and exists as a crystalline, white solid. In chemistry, periodic acid is commonly used for oxidations of alkenes to dialdehydes or diketones, a process called oxidative cis-dihydroxylation.

In histology, periodic acid is used to stain polysaccharides and glycogen by oxidizing these structures, making them accessible for subsequent staining with Schiff's reagent. This is a common method for visualizing glycogen and mucinous substances in tissue sections.