Hydrothermal liquefaction (HTL) of fractionated two types herbaceous biomass (kenaf and miscanthus) by dilute acid, organosolv, alkaline, or demineralization process was carried out under ethanol water co-solvent at 350 degrees C for 30 min to examine the biocrude yield and characteristics. The biocrude properties were comprehensively characterized by HPLC, elemental, GC-MS, and TGA analysis. Fractionation technologies before HTL effectively increased biocrude yield up to 38% compared to that of untreated herbaceous biomass (31%), except for organosolv fractionation of miscanthus, especially, HTL after alkaline fractionation showed high yield and energy recovery ratio up to 70%. Elemental analysis showed that HHV of biocrude was negatively affected by hydrolysis reaction of high lignin content after dilute acid fractionation. The GC-MS analysis revealed that carbohydrates-derived compound significantly increased in the biocrude obtained after organosolv and alkaline fractionation due to holocellulose increases through fractionation process. Additionally, TGA results indicated that the ratio of high-boiling-point compounds in biocrude obtained after demineralization was expanded compared with untreated due to ash removal, which could act as a catalyst. (C) 2020 Elsevier Ltd. All rights reserved.