**Abstract**

Much attention has been focused on reducing the use of petroleum products as fuels, so synthetic gas (Syngas) introduces a great opportunity for energy sustainable developments. Syngas is created either by gasification of plants biomass or waste products (carbon-based) pyrolysis. In principle, Syngas can be produced from any hydrocarbon feedstock. It mainly affects the combustion process in internal combustion engines. The most important is flammability limit, which is very important in the safety and the laminar flame velocity or burning velocity, which is an essential parameter for the investigation of combustion chamber operation and emission performance. This chapter generally reviewed the syngas sources, production, properties, and its importance in the sustainable development for energy.

**Keywords:** synthetic gas (syngas), petroleum products, pyrolysis, gasification, thermo-chemical process, partially combustion, flammability
