The study focuses on investigating the potential of cold water brown macroalgae as a suitable biomass feedstock for biocrude production via supercritical hydrothermal liquefaction (HTL). The work undertook an integration-oriented approach: a bio-refinery concept with demineralisation and high added value product extraction steps prior to residue valorisation in the form of HTL biocrude had been envisioned. The project scope included leaching (water, citric acid and utilising the acidic aqueous byproduct from a continuous HTL setup), alginate extraction via sulphuric acid and sodium carbonate bathing and fucoidan extraction using calcium chloride. Demineralisation was done to identify whether the inorganics (up to 33 wt.\% on dry basis) present in the feedstock are in any way beneficial for effective conversion. The produced 6 sets of biocrudes were characterised by elemental (CHNS) and thermogravimetric (TGA) analysis. Similarly, in order to obtain complete mass balances, all by-products (solid, aqueous and gaseous) were quantified and analysed. A biofuel precursor of acceptable yields and quality was sought. Such a product is also defined by low heteroatom concentrations and high energy recovery (ER). Short HTL (i.e. reaction time of 10 min instead of the baseline 15 min) and the extent of leaching residue neutralisation were also evaluated as a method to improve processing economics and ease potential integration.