Torrefaction is a thermal pretreatment technology. It is also defined as isothermal pyrolysis of biomass occurring in temperature ranges of 200–300°C and performed at atmospheric pressure in the absence of oxygen. Common biomass reactions during torrefaction include devotilization, depolymerization and carbonization of hemicellulose, lignin and noncondensable gases. Typically during torrefaction 70 % of mass is retained as a solid product, containing 90 % of the initial energy content, while 30 % of the lost biomass is converted into condensable and noncondensable products. Torrefaction of biomass improves energy density, grindability, and pelletability index and decreases the moisture content.