Calcination (also referred to as calcining) is a thermal treatment process, in presence of air or oxygen, applied to ores and other solid materials to bring about a thermal decomposition, phase transition, or removal of a volatile fraction. The calcination process normally takes place at temperatures below the melting point of the product materials.

One of the most common applications is as a step in the production of Portland cement, in which calcium carbonate (limestone) is calcined at around 850°C to produce calcium oxide (quicklime) and carbon dioxide.