Lignocellulosic materials are increasingly being developed for conversion to bioethanol due to their abundance and relatively low raw material cost. However, an economically feasible large-scale process for biochemical conversion of lignocellulose has yet to be developed, mostly due to technological challenges in saccharification of the highly recalcitrant material. It has been shown that significant cost-savings can be achieved by operating at solids loadings of greater than 15% dry weight throughout the process due to smaller reactors size requirements and higher product concentrations. However, high solids loadings create issues such as increased energy to mix enzymes into a more viscous and heterogeneous mixture and increased concentration of enzymatic and fermentative inhibitors. Studies have demonstrated decreasing saccharification glucose yields with increasing solids content indicating that there may be mass transfer limitations associated with the process. Lignocellulosic materials contain cellulose, hemicellulose, pectin, and lignin. Water interacts both physically and chemically with these components such that its physical properties vary with location around the cell wall structure. This poster describes studies being conducted to understand the relationship between solids loading, biomass composition, water structuring and diffusivity of enzymes and solubilized sugars, as they relate to overall saccharification efficiency. Nuclear magnetic resonance (NMR) technology is used to investigate the interaction of water within biomass and diffusivities of substances such as glucose. Results show that increasing solids content decreases the diffusivity of glucose and increases the restriction of water contained in cellulose. Better glucose yields during saccharification were found to correspond with less water constraint.