Perchloric acid is an inorganic compound with the formula HClO₄. Usually found as an aqueous solution, this colorless compound is a stronger acid than sulfuric and nitric acid. It is a powerful oxidizer when hot, but its aqueous solutions up to approximately 70 nd room temperature are generally safe, only showing strong acid features and no oxidizing properties. Perchloric acid is useful for preparing perchlorate salts, especially ammonium perchlorate, an important rocket fuel. Overall, perchloric acid is dangerously corrosive and readily forms potentially explosive mixtures.