The objective of this study was to provide a new environmentally friendly and efficient approach for isolating cellulose fibers with minimum structural alteration from wood biomass. The method comprised enzymatic delignification of ionic liquid (IL) swollen wood biomass in ILs-aqueous systems with the aim of overcoming low delignification efficiency associated with the difficulties in enzyme accessibility to the solid substrate and the poor substrate and products solubility in aqueous system. It was found that the cellulose rich wood fibers obtained from biological pretreatment in IL-aqueous systems contained significantly lower amounts of lignin as compared to those found in conventional methods. The treated wood fibers were characterized using Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and X-ray diffractometry (XRD) and compared those with untreated wood fibers. (C) 2011 Elsevier B.V. All rights reserved.