A comprehensive compositional analysis was conducted on biofuel obtained from woody biomass hydroliquefaction in supercritical ethanol with a dispersed Ni-based catalyst. Gas chromatography-mass spectrometry (GC-MS) and H-1 nuclear magnetic resonance (NMR) were used to analyze the bio-oil compositions, and the results indicated the presence of carboxylic acid, ethyl ester, aldehyde, ketone, phenol, and its derivatives. As a result of the inherent limitations of these techniques, an intensive compositional characterization of bio-oil was accomplished through Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). The results revealed that the dominant oxygen-containing compounds were O-2-O-13 with double bond equivalent (DBE) values of 1-20 and carbon numbers of 10-25. The minor N1Ox class species with 4-15 carbon numbers and 10-35 DBE were also detected. The use of FT-ICR MS provided an in-depth compositional analysis of liquefaction-derived oil and would improve the understanding of biocrude for further process upgrading.