The “specific activity” of a cellulase complex during reactions with a lignocellulosic substrate can be improved significantly by changes in the properties of the substrate.  When the components of the cellulase enzyme system encounter a pretreated lignocellulosic substrate, they experience a hierarchy of structural and chemical obstacles that hamper the enzymes’ ability to hydrolyze the cellulose which is confined in a matrix of hemicellulose and lignin. Over the past few decades, it has been quite difficult to predict the ease of hydrolysis of a pretreated lignocellulosic substrate as factors such as crystallinity, DP, accessibility and chemical composition have all been implicated in the contributing to lignocellulosic recalcitrance. Of the factors that affect the efficiency of lignocellulosic hydrolysis, it seems intuitive that the surface area which a substrate possesses which is capable of accommodating cellulase components would play a significant role.  With this in mind, the focus of this presentation will be to explore and assess various measurement techniques to analyze the physical and chemical properties related to “cellulase-accessible” surface area,  such as staining techniques, fiber quality analysis, swelling measurements and x-ray photoelectron spectroscopy, by applying them to various lignocellulosic substrates pretreated by the organosolv and steam explosion pretreatment processes. The information should be valuable to elucidating the substrate related aspects that define the “hydrolytic potential” of the substrate when it comes into contact with the cellulase complex.