Potassium acetate (also called potassium ethanoate), (CH₃COOK) is the potassium salt of acetic acid. It is a hygroscopic solid at room temperature.

It can be prepared by treating a potassium-containing base such as potassium hydroxide with acetic acid:

This sort of reaction is known as an acid-alkalai reaction.

At saturation, the sesquihydrate in water solution (2CH₃COOK·3H₂O) begins to form the semihydrate (2CH₃COOK·H₂O) at 41.3 °C (106.3 °F).

Potassium acetate (as a substitute for calcium chloride or magnesium chloride) can be used as a deicer to remove ice or prevent its formation. It offers the advantages over chlorides of being less aggressive on soils and much less corrosive: for this reason, it is one of the preferred substances for removal of ice from airplanes and airport runways.

Potassium acetate is the extinguishing agent used as a component in some Class K fire extinguishers because of its ability to cool and form a crust over burning oils.^{[citation needed]}

Potassium acetate is used in processed foods as a preservative and acidity regulator. In the European Union, it is labeled by the E number E261; it is also approved for usage in the USA, Australia, and New Zealand.

In molecular biology, potassium acetate is used to precipitate Sodium dodecyl sulfate (SDS) and SDS-bound proteins to allow their removal from DNA.^{[citation needed]}