Ultrasound-assisted alkaline pretreatment of sugarcane bagasse (SCB) for fermentable sugar productionwas carried out and the influence of particle size, liquid to solid ratio (LSR), NaOH concentration, temper-ature and sonication time on delignification and reducing sugar production was ascertained withPlacket–Burman design. The best combination of each significant factor was determined by a centralcomposite design (CCD) and optimum pretreatment conditions for maximum reducing sugar yield(96.27%) were particle size of 0.27 mm, LSR of 25 ml/g, NaOH concentration of 2.89% (w/v), temperatureof 70.15°C and pretreatment time of 47.42 min. Under these conditions, 92.11% of theoretical reducingsugar yield was observed experimentally. The substantial reduction in pretreatment time and tempera-ture with improved efficiency is the most attractive features of the ultrasound-assisted alkalinepretreatment