To meet the expected requirements of the proposed EU Renewable Energy Directive for the next decade (RED II), it is necessary to increase the availability of second-generation biofuels. One promising way of doing this involves using ablative fast pyrolysis units to transform an agricultural by-product, for example straw, into bio-oil. To obtain straw bio-oil suitable for processing in a typical refinery, we optimized the key parameters of its hydrotreatment. For the upgrading, a continuous flow reactor with a fixed bed of a commercial sulphide NiMo/Al2O3 catalyst was used. The reaction temperature and pressure were tested at 240-360 degrees C and 2-8 MPa, respectively. The reaction off-gas was analysed by GC-FID/TCD. A detailed physicochemical analysis of the products was carried out. Under most conditions tested, the product was separated into an aqueous and an organic phase. For the best products, > 85% of the feed energy content remained in the organic phase and a significant decrease in viscosity and acidity was achieved. The product prepared at 360 degrees C and 8 MPa was the only one completely miscible with straight-run gas oil and, thus, appears to be the most suitable for co-processing in a refinery.