To investigate the effect of pretreatment on morphological fea-tures and surface characteristics of rice straw, SEM images ofuntreated and treated straw with 0.5 M Na2CO3at 100◦C for 3 hwere captured (Fig. 2). Significant morphological modification canbe observed by comparing the images. As it can be seen, the packedstructure of the rice straw was opened up and silica layer on theouter layer of straw was disappeared by the pretreatment whichcan provide more accessible surface for the hydrolytic enzymes.