Name Potassium hydroxide
Chemical formula KOH
Appearance White solid


Formula weight 56.1 amu
Melting point 679 K (406 °C)
Boiling point 1593 K (1320 °C)
Density 2.0 ×103 kg/m3
Crystal structure ?
Solubility 119 g in 100g water


ΔfH0gas -232 kJ/mol
ΔfH0liquid -415.6 kJ/mol
ΔfH0solid -425 kJ/mol
S0solid 79 J/mol·K


Ingestion Very dangerous, may cause permanent GI damage, even death.
Inhalation Very dangerous, high doses may cause serious injury. Long-term hazards also known.
Skin Causes burns, ranging from a rash up to deep ulcers.
Eyes As for skin, may cause irreversible damage.
More info Hazardous Chemical Database
SI units were used where possible. Unless otherwise stated, standard conditions were used.

Disclaimer and references

The chemical compound potassium hydroxide, (K OH) sometimes known as caustic potash, potassa, potash lye and potassium hydrate, is a metallic base. It is a very alkaline compound used in agriculture to correct the pH of acidic soils. It can also be used as a fungicide or even an herbicide.


It is a major industrial chemical used as a base in a wide variety of chemical processes.

It is used as a catalyst in reactions like the production of biodiesel, because it dissolves in methanol much more easily than NaOH, and it doesn't "clump".

Some uses of KOH include acrylate ester copolymer coating, defoaming agents used in the manufacture of paper, formulation aid for food, pH control agent, polyethylene resins, textile processing.

Food uses include washing or chemical peeling of fruits and vegetables, chocolate and cocoa processing, caramel color production, poultry scalding, and forming a skin on pretzels before baking, olive ageing, soft drink processing, ice cream thickener.

Other uses include in veterinary medicine in disbudding calves horns and to dissolve scales and hair; manufacture of cleansers; in wart removal and as a cuticle solvent. This type of compound is also used in washing powders, some denture cleaners, non-phosphate detergents, and drain or pipe cleaners.