A study on hemicellulose extraction from 10 different tree species was performed using a batchwise operated cascade reactor constituted by 5 units of 200 mL and a buffer vessel of 2000 mL where a flowrate of 150 L h−1 was fully recirculated (close loop operatioin). The experiments were performed at 160 °C, 9 bar and with wood chips particle size of 1.25–2 mm (average solid load of 6.57 g/L). The aim was to identify which wood species were the best candidates to obtain a high yield and/or molecular weight of hemicelluloses. Hydrothermal extractions at different times (from 5 to 80 min) were investigated. The highest yield was obtained with eucalyptus wood (40.3 wt%) after 80 min of extraction. Furthermore, 3 different trends were obtained for molecular weight evolution, where the different tree species can be grouped.