Among the various renewable energy sources, synthesis gas (syngas) offers a promising opportunity for sustainable development in the energy and transportation sectors. Syngas can provide an economically viable solution, in the areas where the price of petroleum and diesel fuels are high, or where supplies are unreliable. This paper contains the information regarding the effect of particle size, and the moisture content of feedstock on the quality of producer gas. Coupling of syngas to the internal combustion engines (ICEs) is a feasible technology for the generation of heat and power on a small scale. Here, effect of syngas addition on performance of a spark ignition (SI) engine and compression ignition (CI) engine is also studied. This review also presents combustion features like calorific value, laminar flame velocity and flammability limits of syngas and its effects on the combustion in an internal combustion engines.