Hydrogen fluoride is a colorless, fuming liquid or gas with a strong, irritating odor. It is usually shipped in steel cylinders as a compressed gas. Hydrogen fluoride readily dissolves in water to form colorless hydrofluoric acid solutions; dilute solutions are visibly indistinguishable from water.Hydrofluoric acid. A solution of hydrogen fluoride in water. It is a colorless fuming liquid which can cause painful burns.

Hydrofluoric acid is an aqueous solution of hydrogen fluoride gas. It plays an important role in the purification of aluminum and uranium. It is also used to etch glass for carving patterns, marking scales, characters, and so on. In the semiconductor industry, it is used to remove oxides from silicon surfaces. In refineries, it can serve as a catalyst for the alkylation of isobutane and n-butene. Hydrofluoric acid is also employed in the "pickling" process to remove oxygen-containing impurities from stainless steel surfaces.