Thermal decomposition

Thermal decomposition, also called thermolysis (roughly "to break with heat"), is a process where heat causes a chemical compound to break down into simpler chemical compounds or elements.Kerry K. Karukstis; Gerald R. Van Hecke, Chemistry Connections: The Chemical Basis of Everyday Phenomena (Boston: Academic Press, 2003), p. 63

 Types 
If the compound is exposed to oxygen, usually from the air, the reaction is called calcination. If an inert gas is used instead of air, it is pyrolysis.

Cracking is the thermolysis of large molecules like hydrocarbons, with or without a catalyst.

 References 

Category:Chemical processes