The majority of the potassium chloride produced is used for making
potash, since the growth of many
plants is limited by potassium availability. The two main types of potash are: Muriate of Potash (MOP, Potassium Chloride) and Sulphate of Potash (SOP, Potassium Sulphate). While SOP typically sells at a premium to MOP, the vast majority of potash fertilizer worldwide is sold as MOP.
Potassium is vital in the
human body, and potassium chloride by mouth is the common means to treat
low blood potassium, although it can also be given
intravenously. It can be used as a
salt substitute for
food, but due to its weak, bitter, unsalty
flavor, it is usually mixed with ordinary table salt (sodium chloride) to improve the
taste. The addition of 1 ppm of
thaumatin considerably reduces this bitterness.
 Complaints of bitterness or a chemical or metallic taste are also reported with potassium chloride used in food.
As a chemical
feedstock, it is used for the
potassium hydroxide and
potassium metal. It is also used in medicine,
soaps, and as a sodium-free substitute for
table salt for people concerned about the health effects of sodium.
It is used as a supplement in animal feed to boost the amount of nutrients in the feed, which in turn promotes healthy growth in animals. As an added benefit, it is known to increase milk production.
It is sometimes used in
water as a
completion fluid in
natural gas operations, as well as being an alternative to
sodium chloride in household
water softener units.
Glass manufactures use granular potash as a flux, lowering the temperature at which a mixture melts. Because potash confers excellent clarity to glass, it is commonly used in eyeglasses, glassware, televisions and computer monitors.
KCl is useful as a
beta radiation source for
radiation monitoring equipment, because natural potassium contains 0.0118% of the
isotope 40K. One
kilogram of KCl yields 16350
radiation consisting of 89.28% beta and 10.72%
gamma with 1.46083 MeV.
Potassium chloride is used in some
de-icing products that are designed to be safer for pets and plants, though these are inferior in melting quality to
calcium chloride [lowest usable temperature 12 °F (−11 °C) v. −25 °F (−32 °C)]. It is also used in various brands of
bottled water, as well as in bulk quantities for
Potassium chloride was once used as a
fire extinguishing agent, used in portable and wheeled
fire extinguishers. Known as Super-K dry chemical, it was more effective than
sodium bicarbonate-based dry chemicals and was compatible with
protein foam. This agent fell out of favor with the introduction of
potassium bicarbonate (
Purple-K) dry chemical in the late 1960s, which was much less
corrosive and more effective. It is rated for B and C fires.
sodium chloride and
lithium chloride, potassium chloride is used as a
flux for the
gas welding of
Potassium chloride is also an optical crystal with a wide transmission range from 210 nm to 20 µm. While cheap, KCl crystal is
hygroscopic. This limits its application to protected environments or short-term uses such as prototyping. Exposed to free air, KCl optics will "rot". Whereas KCl components were formerly used for
optics, it has been entirely replaced by much tougher crystals such as
Potassium chloride has also been used to produce
heat packs which employ
 but these have mostly been discontinued with the advent of cheaper and more efficient methods, such as the oxidation of metals ('Hot Hands' one-time-use products) or the
sodium acetate (multiple-use products).
Potassium chloride is used as a
scotophor with designation P10 in
dark-trace CRTs, e.g. in the