AbstractThe thermal degradation of cellulose is an important process in several fields such as the paper industry, biomass combustion, fire retardation, etc. Paper consists mostly of cellulose fibres. Although the fibre source has changed continiously from cotton or linen rags to wood, its nature is still vegetal. Pyrolysis in combination with gas chromatography and mass spectrometry has been used to identify the structures of thermal degradation products with the aim to characterize papers used in different centuries. Pyrolysis of cellulose has also been studied in the presence of the methylating reagent tetramethylammonium hydroxide (TMAH).