**Abstract**

Chemical recycling is one of the most intensively developed potential solutions for the global plastic waste issue. This broadly defined term covers several different technologies that lead to many diverse products. Polyolefins (polyethylene and polypropylene) can be chemically recycled by pyrolysis (cracking) or gasification. These polymers' chemical composition and structure make them a great potential source of valuable hydrocarbons or carbon atoms for syngas production. Thermal and catalytic cracking of polyethylene and polypropylene can be optimised to maximise specific types of hydrocarbons that, after optional additional processing, such as hydrotreatment, steam cracking or distillation, can be used as intermediates in petrochemical plants, fuels or fuel components, monomers for polymerisation of new, virgin polymers or as specialty chemicals (final market products). Gasification of plastic waste transforms polymers into a mixture of hydrogen, carbon monoxide and carbon dioxide, which can be further used as a source of these gasses, transformed into chemicals and fuels, or used directly to produce energy. This chapter presents all of these process paths with examples of existing technologies and their level of technology readiness and perspectives for scale-up.

**Keywords:** polyolefins, polyethylene, polypropylene, chemical recycling, pyrolysis, thermal cracking, catalytic cracking, gasification
