Cellulose crystallinity poses a substantial barrier to the enzymatic digestion of biomass to its constituent glucose. To overcome this crystallinity, uneconomically large cellulase enzyme loadings are required to digest the material.  Conventional pretreatment technologies generally only cause a transient decease in cellulose crystallinity.  The goal of these studies is to identify conditions to decrystallize cellulose that are compatible with enzyme digestion. The Flory-Huggins solvent-polymer interaction parameter indicates that water is a poor solvent for cellulose while several organic solvents were identified as possible good solvents for cellulose.  To test the efficacy of these solvents for preventing crystallization during precipitation and washing, cellulose was first decrystallized by dissolving microcrystalline cellulose in phosphoric acid (PASC) and then the impact of these solvents on recrystallization of PASC evaluated.  As predicted by the F-H theory, several solvents were identified that appeared to prevent PASC from recrystallizing during washes.  Cellulose did not precipitate when treated with these solvents but instead formed a gel. Fractal analysis of small angle neutron scattering (SANS) by solvent-treated cellulose indicates cellulose polymers in these solvents have the I(q) vs q scaling property of a swollen coil in solution.  Fourier transform infrared resonance (FTIR) confirmed the modification of hydrogen bond networks. The activity of Saccharophagus degradans Cel5H, a processive endoglucanase biased toward amorphous cellulose, increased 1500-fold when solvent-treated cellulose was used as the substrate.   The results indicate that solvent manipulation can be used as part of a pretreatment process to stably decrystallize cellulose.