Pyrolysis is the chemical decomposition of organic materials by heating in the absence or controlled amount of oxygen. Pyrolysis and gasification are thermo-chemical conversion routes which recovers energy from biomass and waste fuels. Pyrolysis is heavily used in the chemical industry, for example, to produce charcoal, activated carbon, methanol and other chemicals from wood. It is an important chemical process in several cooking procedures such as baking, frying and grilling. Pyrolytic processes are involved in basic research as well as in applied fields such as the industry. This book will survey the use of the pyrolysis in these fields and will also examine current research done in the nanoscience field.