What Is Potassium Oleate?

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Unlike potassium chloride and potassium gluconate, potassium oleate is not a dietary supplement. This chemical is known by a variety of names, including assium 9-octadecenoate, OS soap, trenmine and the potassium salt of oleic acid. Found in many foods and cosmetics, potassium oleate also occurs naturally in the bodies of insects.


Potassium oleate is both a salt and a fatty acid. It is a salt because it is the product of an acid and a base. It is a fatty acid because it has a long carbon backbone with a carboxyl group terminus. Potassium oleate has a molecular weight of 321.62 and a melting point of 428 degrees Fahrenheit. It dissolves freely in water to produce mildly basic solutions with a pH higher than 7.

Cosmetic Uses

Potassium oleate is used as an emulsifier in many liquid soaps, facial cleansers, mustache waxes, body washes and hair permanents. Emulsifiers act like surfactants and reduce the surface tension of a liquid. Potassium oleate prevents the ingredients in these products from separating into separate chemicals.

FDA Approval

The FDA says potassium oleate "may be safely used in food and in the manufacture of food components" as long as it is used as "a binder, emulsifier and anticaking agent," and the product is properly labeled. The use of potassium oleate in food requires the use of food grade chemicals, which have a higher purity than many other grades of reagents.

Dead Bug Walking

Chemical company Triveni Interchem reports that dead bodies of bees and Pogonomyrmex ants emit potassium oleate as they decay. Other insects respond to the smell of this chemical by removing the body of the dead insect from the nest or hive. If you brush the body of a live bee or ant with oleic acid, other insects will remove it from the hive or nest as if it were dead.