The focus of the treatise is the production of biomethane as a result of upgrading biogas obtained from the anaerobic digestion of the organic fraction of municipal solid wastes. The main characteristics, with advantages and disadvantages, of the biogas and of the biomethane have been analysed, with a focus on the sustainable development goals and on the legislation aimed to incentive these new energy vectors. Furthermore, the main technologies for upgrading biogas have been described, such as amine scrubbing, membrane separation, water scrubbing, organic physical scrubbing, pressure swing adsorption. The technical data, used in the treatise, derives from the operation of the upgrading plant, situated in Foligno (PG) and managed by Asja Ambiente Italia S.p.A, whose processes have been analysed in depth.