We commenced our studies with beechwood sawdust, a lignocellulosic biomass. Initial investigations revealed that the combination of Ru-MACHO-BH and H3PO4(aq) is catalytically active under a H2 pressure for the transformation to GVL. Hence, we first investigated the effect of H3PO4(aq) concentration while maintaining the catalyst loading, H2 pressure, and reaction temperature constant at 0.5 mol%, 30 bar, and 140 °C, respectively. Gratifyingly, employing 7.5 M H3PO4(aq) led to an encouraging 15 wt% yield of GVL after 96 hours (Table , Entry 1), which was improved to 23 wt% by increasing the concentration of H3PO4(aq) to 9.3 M (Entry 3). Shortening or extending the reaction time to 24 or 168 hours, respectively, did not significantly change the yield (Entries 2 and 4). Further increasing the H3PO4(aq) concentration to 10.1 M improved the yield to 25 wt%, which decreased again upon longer reaction times (Entry 5 versus Entries 6 and 7). With 10.9 M H3PO4(aq), the optimal yield of 26 wt% was obtained after 24 hours (Entry 9). Considering that the theoretical weight of GVL from beechwood is limited to 54wt% (assuming completely dry biomass and that only hemicellulose and cellulose are converted to GVL ), the yield is 48%. Again, both shortening and extending the reaction time resulted in lower yields (Entries 8 and 10). Moreover, after 18 hours, we still detected the intermediate LA, which was fully converted after 24 hours. It is noteworthy to mention that no hydrodeoxygenation products, such as hydrocarbons, were observed under these reaction conditions, neither in the liquid nor gas phase (SI, Figure ). Furthermore, a control experiment with GVL as substrate and otherwise identical conditions (Ru-MACHO-BH, 10.9 M H3PO4(aq), 30 bar H2, 140 °C, 72 hours) showed no decomposition products (SI, Figure , S26), underpinning the strong selectivity towards GVL production. When the catalyst loading was reduced to 0.9 wt%, the reaction afforded 15 wt% GVL under the optimized reaction conditions after 120 hours. However, LA was still detected in the reaction medium, suggesting the reaction had not finished. Finally, the reaction was also carried out in an EtOH/H2O mixture to study the solvent effect. With 1:1 V/V EtOH/H2O, a lower GVL yield of 14 wt% was observed under otherwise optimized conditions (Entry 11). Table . Optimization of the direct conversion of beechwood sawdust to GVL.