Potassium hydroxide, also known as lye is an inorganic compound with the chemical formula KOH. Also commonly referred to as caustic potash, it is a potent base that is marketed in several forms including pellets, flakes, and powders. It is used in various chemical, industrial and manufacturing applications. Potassium hydroxide is also a precursor to other potassium compounds. Potassium hydroxide is used in food to adjust pH, as a stabilizer, and as a thickening agent. This ingredient has been considered as generally safe as a direct human food ingredient by the FDA, based upon the observance of several good manufacturing practice conditions of use.

In addition to the above uses, potassium hydroxide is also used in making soap, as an electrolyte in alkaline batteries and in electroplating, lithography, and paint and varnish removers. Liquid drain cleaners contain 25 to 36% of potassium hydroxide .

Medically, potassium hydroxide (KOH) is widely used in the wet mount preparation of various clinical specimens for microscopic visualization of fungi and fungal elements in skin, hair, nails, and even vaginal secretions.

Potassium hydroxide, also known as KOH or caustic potash, has many uses due to its properties as a strong alkali or base: 

Cleaning

KOH is corrosive, highly soluble in water, and thermally stable, making it a good grease remover. It creates an emulsion that suspends oily or solid particles in wash water. 

Agriculture

KOH is used to adjust soil pH, produce fertilizers, and detoxify glycerine for animal feed. Its low salt index and high solubility make it ideal for liquid fertilizer mixtures, especially for crops that can't tolerate chloride ions. 

Soap making

KOH is an essential ingredient in making soft and liquid soaps through saponification. 

Batteries

KOH is used as an electrolyte in alkaline batteries, helping ions flow between the positive and negative terminals. 

pH regulation

KOH is used as a pH regulator in industrial manufacturing and processing. In the food industry, it's used as a pH control agent. 

Other uses

KOH is also used in chemical manufacturing, petrochemical refining, cleansing solutions, chip fabrication for semiconductors, paint and varnish removers, and cuticle removers.