Biomass is a renewable source of fuel and fine chemicals. Although naturally abundant, it is heterogeneous and recalcitrant to biodegradation. Current industrial strategy is to separate individual components before conversion. A major challenge is to find low-cost solvents with optimized extraction efficiency.Ionic liquids (ILs) are salts that melt near room temperature. Bio-based ILs, such as cholinium lysinate, are non-toxic, renewable and inexpensive. They are the next generation of sustainable solvents for lignin extraction. We will examine the structure of mixtures of ILs with model lignin residues and water. This will enable us to understand the dominant intermolecular forces during the extraction process, and the influence of IL structure on extraction efficiency. This structural insight will facilitate future design of sustainable solvents for biomass processing.