A lime kiln is a kiln used for the calcination of limestone (calcium carbonate) to produce the form of lime called quicklime (calcium oxide). The chemical equation for this reaction is
:CaCO + heat → CaO + CO
This reaction can take place at anywhere above , but is generally considered to occur at  (at which temperature the partial pressure of CO is 1 atmosphere), but a temperature around  (at which temperature the partial pressure of CO is 3.8 atmospheres) is usually used to make the reaction proceed quickly. Excessive temperature is avoided because it produces unreactive, "dead-burned" lime.
Slaked lime (calcium hydroxide) can be formed by mixing quicklime with water.