It decomposes rapidly on standing to bromic acid and oxygen, which releases toxic brown bromine vapors.

Perbromic acid solutions greater than 6M are unstable in air, where an autocatalytic decomposition of the compound will occur.

Perbromic acid was discovered through the decay of a radioactive selenate sample, SeO4−2, where bromine crystals were exposed to gamma radiation.

Perbromic acid is corrosive and an irritant, therefore it is extremely dangerous to the skin, eyes, airways, and digestive tract.

Due to its toxicity, prolonged or repeated exposure could also lead to organ damage via the lungs, kidneys, and intestines.