Calcination is a process of heating a solid chemical compound to a high temperature without melting under restricted supply of ambient oxygen, generally for the purpose of removing impurities or volatile substances. The process of calcination derives its name from the Latin word "calcinare," which means "to burn lime" due to its most common application, the decomposition of calcium carbonate (limestone) to calcium oxide (lime) and carbon dioxide, in order to create cement. The product of calcination is usually referred to as "calcine," regardless of the actual minerals undergoing thermal treatment.

Calcination is carried out in furnaces or reactors of various designs including shaft furnaces, rotary kilns, multiple hearth furnaces, and fluidized bed reactors. The process of calcination is used in various industries, including cement production, metal extraction, and chemical manufacturing. Some common examples of calcination include the decomposition of carbonate ores, such as the calcination of limestone to drive off carbon dioxide, and the removal of water of crystallization in the form of water vapor from materials like bauxite and gypsum.

Calcination is sometimes considered a process of purification, as it can remove volatile substances, oxidize a portion of mass, or render materials friable. The term "calcination" is often used interchangeably with other thermal treatment processes, despite not meeting the technical definition of a true calcination process.