To realize a high-value utilization of the water-insoluble phase of bio-oil, acid and alkaline solutions combined with organic solvents have been employed to separate the monophenols and pyrolytic lignins from this phase. The phenolic fraction B, obtained by reactive extraction of the water-insoluble phase, was found to be rich in phenolic compounds, with a high concentration of 94.35%, wherein the content of guaiacols reached 48.27%. Furthermore, Fourier-transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR), and gel-permeation chromatography (GPC) analyses of the pyrolytic lignins showed the primary structural units to be of the guaiacol and syringol types. Polymers with molecular weight higher than 1000 dominated in the high-molecular-weight pyrolytic lignin, whereas the low-molecular-weight pyrolytic lignin contained more reactive phenolic hydroxyl groups. (c) 2013 Elsevier B.V. All rights reserved.