Rice straw (RS) is one of the most abundant lignocellulosic crop residues in the world. Its annual production is about 731 million tons which is distributed in Africa, Asia, Europe and America. This amount of RS can potentially produce 205 billion liters of bio-ethanol per year. Rice straw is composed of cellulose (41%) and hemicellulose (20%) which is bound to lignin
(12%) by hydrogen and covalent bonds. The content of lignin in RS is less than that in other common feedstocks, such as corn stover and wheat straw. Enzymes cannot effectively convert lignocellulosic biomass to fermentable sugars without pretreatment. An effective pre-treatment of rice straw can be achieved with alkaline solutions like NaOH or KOH to remove lignin and a part of the hemicellulose, and to efficiently increase access of enzyme to cellulose. Compared with acid and oxidative reagents, alkali treatment appears to be the most effectiven method in breaking the ester bonds between lignin, hemicellulosesand cellulose, and in avoiding fragmentation of the hemicelluloses polymers