Lithium hexafluorosilicate is an inorganic chemical compound with the chemical formula Li₂SiF₆.

Lithium hexafluorosilicate can be obtained by reacting hexafluorosilicic acid with lithium hydroxide or lithium carbonate or by reacting silicon tetrafluoride with lithium fluoride.

Lithium hexafluorosilicate is a white, odorless solid that is soluble in water and methanol. When heated above 250 °C, it decomposes into lithium fluoride and silicon(IV) fluoride. It has a trigonal crystal structure with the space group P 321 (space group no. 150) and three formula units per unit cell, isotypic to sodium hexafluorosilicate.

Lithium hexafluorosilicate is used as an intermediate in the manufacture of pharmaceuticals and other chemical compounds. It is also an intermediate in the preparation of lithium chloride from lithium-containing minerals by reacting with hexafluorosilicic acid.^{[citation needed]}