Ionic liquids (ILs) are organic molten salts and show promise as solvents for lignocellulosic materials. The solubilities of lignocellulose components as a function of anion and cation properties are not well understood. Our objective is to obtain the thermodynamic phase behavior for lignocellulose in various ILs and ILs with organic cosolvents. This will help identify ionic liquid-cosolvent combinations that are efficient for biomass dissolution and separation of its components. The values of infinite dilution activity coefficients for various organic co-solvents in ionic liquids, the solubilities of sugars such as xylose, arabinose and glucose in ionic liquid-cosolvent combinations are predicted by a priori thermodynamic models (COSMO-RS, conductor-like screening models – real solvents). In addition, from COSMO-RS calculations, we provide QSPR (quantitative structure property predictions) of several ionic liquids, cosolvents and saccharides. Toward depolymerization of both the cellulosic and lignin components of biomass , ionic liquids have been screened for maintenance of enzyme stability and activity. GFP fluorescence has been employed as a reporter of enzyme stability. While imidazolium-based ILs showed a loss of conformation after 30 minutes, IL/cosolvent solutions were able to retain protein conformation.