Pyrolysis

Burning pieces of wood, showing various stages of pyrolysis, followed by oxidative combustion

Pyrolysis (/paɪˈrɒlɪsɪs/; from Ancient Greek πῦρ (pûr) 'fire' and λύσις (lúsis) 'separation') is a process involving the separation of covalent bonds in organic matter by thermal decomposition within an inert environment without oxygen.