Hexafluorosilicic acid is an inorganic compound with the chemical formula  (also written as ). It is a colorless liquid rarely encountered undiluted. Hexafluorosilicic acid has a distinctive sour taste and pungent smell. It is mainly produced as a precursor to aluminum trifluoride and synthetic cryolite. It is commonly used as a source of fluoride for water fluoridation. Concentrated hexafluorosilicic acid is corrosive and can attack the skin, but in everyday use, it is so diluted as to be harmless.

Hexafluorosilicic acid is an inorganic compound with the chemical formula  (also written as ). It is a colorless liquid rarely encountered undiluted. Hexafluorosilicic acid has a distinctive sour taste and pungent smell. It is mainly produced as a precursor to aluminum trifluoride and synthetic cryolite. It is commonly used as a source of fluoride for water fluoridation. Concentrated hexafluorosilicic acid is corrosive and can attack the skin, but in everyday use, it is so diluted as to be harmless.