Potassium chloride (also known as Sylvite, KCl, or potassium salt) is a metal halide salt composed of potassium and chlorine. It is odorless and has a white or colorless vitreous crystal appearance. The solid dissolves readily in water, and its solutions have a salt-like taste. Potassium chloride can be obtained from ancient dried lake deposits. KCl is used as a fertilizer, in medicine, in scientific applications, and in food processing, where it may be known as E number additive E508.
In a few states of the United States, it is used to cause cardiac arrest, as the third drug in the "three drug cocktail" for executions by lethal injection. It occurs naturally as the mineral sylvite, and in combination with sodium chloride as sylvinite.