Potassium chloride (KCl), also known as potassium muriate and sylvite, is a white or colorless vitreous solid. It is soluble in water and has a salty taste. It is used in fertilizers, medicine, laboratory chemicals, photography, and as a substitute for sodium chloride in cooking.

The melting point of KCl is 776 deg C. When melted, it forms a colorless solution that conducts electricity. It is mined from the minerals sylvite and carnallite; or extracted from salt lakes by flotation and electrostatic separation. It can also be produced from sodium hydroxide by reacting it with chlorine gas generated by the electrolytic process of nitric acid production.

KCl crystals have a face-centered cubic structure and cleave easily in three directions. In powdered form, it emits a lilac flame when burned. It is a common reference material for measuring the electrical conductivity of solutions, because aqueous solutions are fully ionized into solvated K+ and Cl- ions and therefore show no net conductivity.

Intentional lethal injections of KCl can be used for both suicide and murder. In one study, macroscopic and histological examination of fetuses after medical termination for serious disease found clumps of lanceolate KCl crystals in internal organs. In another study, a lethal injection of KCl was reported to have been a means of suicide in two cases. The authors report that the occurrence of such crystals in fetuses makes the use of KCl as a means of suicide or homicide a particularly hazardous method of death.