Biofuel technology seems to be a promising method for economically and environmentally prospective treatments of lignocellulosic wastes from various branches like food processing, forestry, or agriculture. Factors like the lignin content, crystallinity of cellulose, and particle size, limit the digestibility of hemicellulose and cellulose present in lignocelluloses. Biomass size reduction is a mechanical treatment process which due to increasing of the accessible surface area and decreasing of cellulose crystallinity improves the digestibility and the conversion of saccharides during hydrolysis. Informations about equipment design parameters and energy requirements are reviewed in relation to initial and final particle sizes, bulk density, and moisture content in biomass.