Hydrothermal Liquefaction (HTL) is a versatile thermochemical pathway that converts wet or moist biomass into a bio-oil with promising properties as a future replacement of fossil oil. Lignocellulosic biomasses are of particular interest as they are representative of almost all terrestrial plant material. The fibrous nature of lignocellulosic biomass may however induce clogging and damage in continuous HTL reactors systems. This study investigates the pretreatment of Miscanthus x Giganteus (a perennial grass) in order to achieve stable feedstock slurries. To this end, the stabilizing effects of homogeneous catalysts are studied as well as the use of carboxymethyl cellulose as additive to prevent sedimentation. Finally, the impact of the applied pretreatment methodologies on the HTL process was evaluated with particular emphasis on product distribution and carbon balances. (C) 2016 Elsevier Ltd. All rights reserved.