This chapter highlights the pivotal roles of biomass preprocessing techniques for improving the performance efficiency and economy of biomass gasification process. It describes the effects of preprocessing techniques such as size reduction and pelletization on the biomass gasification process and the economic value of the syngas produced from biomass. The chapter provides key insight about how one or combination of preprocessing techniques can noticeably enhance the overall performance of the biomass gasification process. Gasification, pyrolysis, hydrothermal liquefaction, torrefaction, and combustion are the various biomass thermochemical technologies commonly used in development stages. The reason for the pressure drop was related to the dust formation, as biomass pellets were likely to break up under mechanical and thermal stresses. Diverse lignocellulosic biomass materials are the potential energy feedstocks for production of biofuels and value-added bioproducts, and further to mitigate the emission of greenhouse gas such as CO₂.