Calcium hydroxide, slaked or hydrated lime, is an inorganic compound with the Calcium Hydroxide Calcium Hydroxide chemical formula Ca(OH)2. Calcium hydroxide has many names, including builders’ lime, caustic lime, slaked lime, cal, and pickling lime. It is used in various applications, including food preparation, where it has been identified as E number E526.

Calcium Hydroxide adopts a polymeric structure similar to magnesium hydroxide (brucite structure). The compound has two hydroxide ions (OH–) for each ion of calcium (Ca2+).

The compound’s density is approximately 2.211 g/cm³ in solid form. It has a melting point of 580 °C (1,076 °F; 853 K), at which it loses water and decomposes.