Potassium hydroxide is strongly alkaline and corrosive, and its properties are similar to sodium hydroxide, which can cause burns. It can absorb water and dissolve in the air, and absorb carbon dioxide to gradually become potassium carbonate. The pH of the 0.1 mol/L solution is 13.5.

White oblique crystals, industrial products are white or light gray lumps or rods. Easily soluble in water, emits a lot of heat of dissolution when dissolved, soluble in ethanol, slightly soluble in ether. It is deliquescent and has strong water absorption.

The properties are similar to sodium hydroxide, which is strongly alkaline and corrosive. The pH of a 0.1 mol/L solution is 13.5. It is easy to absorb moisture in the air and deliquescence, absorbing carbon dioxide to form potassium carbonate. It is soluble in about 0.6 parts of hot water, 0.9 parts of cold water, 3 parts of ethanol, 2.5 parts of glycerin, and slightly soluble in ether. A lot of heat is generated when dissolved in water, alcohol or treated with acid. Moderately toxic, LD50 (rat, oral) 1230 mg/kg.