Periodic acid is found as a colorless solution. It is a strong oxidizing agent, like perchloric acid. It breaks down when heated to iodine pentoxide and oxygen, as well as water. It does not form I2O7. It is found as HIO4 in dilute solution and H5IO6 in concentrated solution. When H5IO6 is heated, it turns into HIO4.
It is made by reacting a periodate with a strong acid.
It is used to look at the structure of certain organic compounds.