Cereal straws are lignocellulosic materials with a high content of hemicellulose compared to cellulose (see Table 3.11). The straws comprise the dry stalks of a cereal plant, crushed or not, after the grain or seed has been removed. The wheat straw presents a great availability due to the vast cultivated volume of this grain in the world (about 813 million ton per year of straw). In the United States, about 33 million ton of wheat straw is available, assuming that 40% of total straw is collectable in a sustainable way (Kadam and McMillan, 2003). This amount of straw is equivalent to 9.6 million L of ethanol if considering an ethanol yield from wheat straw of 261.3 L/ton. Rice straw is another source of lignocellulosic biomass with a high availability in the world (779 million ton). In particular, the increase in environmental controls is phasing out the practice of burning rice straw in the open air. These regulations contribute to the search for new applica­tions for these types of residues.