Interactions determining the dissolution of a monomer of β-cellulose, i.e., cellobiose in a room temperature ionic liquid, [Emim][OAc], have been studied using ab initio molecular dynamics simulations. Although anions are the predominant species in the first coordination shell of cellobiose, cations too are present to a minor extent around it. The presence of low concentration of water in the solution does not significantly alter the nature of the coordination environment of cellobiose. All intra-molecular hydrogen bonds of anti–syn cellobiose are replaced by inter-molecular hydrogen bonds formed with the anions, whereas the anti–anti conformer retains an intramolecular hydrogen bond.