The pretreatment of yellow poplar wood sawdust using liquid water at temperatures above 220 degrees C enhances enzyme hydrolysis. This paper reviews our prior research and describes the laboratory reactor system currently in use for cooking wood sawdust at temperatures ranging from 220 to 260 degrees C. The wood sawdust at a 6-6.6% solid/liquid slurry was treated in a 2 L, 304 SS, Parr reactor with three turbine propeller agitators and a proportional integral derivative (PID) controller, which controlled temperature within +/-1 degrees C. Heat-up times to the final temperatures of 220, 240, or 260 degrees C were achieved in 60-70 min. Hold time at the final temperature was less than 1 min. A serpentine cooling coil, through which tap water was circulated at the completion of the run, cooled the reactor’s contents within 3 min after the maximum temperature was attained. A bottoms port, as well as ports in the reactor’s head plate, facilitated sampling of the slurry and measuring the pH, which changes from an initial value of 5 before cooking to a value of approx 3 after cooking. Enzyme hydrolysis gave 80-90% conversion of cellulose in the pretreated wood to glucose. Simultaneous saccharification and fermentation of washed, pretreated lignocellulose gave an ethanol yield that was 55% of theoretical. Untreated wood sawdust gave less than 5% hydrolysis under the same conditions.