This study presents the ultrasound assisted metal chloride treatment of sugarcane bagasse (SCB) for bioethanol production. The operating parameters pertaining to pretreatment and enzymatic saccharification were optimized. The ultrasound assisted FeCl3 pretreatment (UAFP) showed the maximum cellulose recovery and delignification of 94.94 and 79.42%, respectively, at the optimum conditions (Particle size 0.274 mm, H2O2 concentration 1.5% v/v, substrate dosage 3 g, ultrasound time 75 min, molar ratio of FeCl3 and H2O2 1:100 and temperature 60 degrees C). Enzymatic saccharification of SCB obtained from UAFP showed 96% glucan digestibility (D-G) with 15 FPU cellulase and 30 IU beta-glucosidase. The hydrolyzate obtained was fermented using Saccharornyces cerevisiae and about 93% theoretical ethanol yield was achieved at the end of 72 h of fermentation. The structural changes of native and pretreated SCB were investigated by Fourier transform infrared spectroscopic analysis (FTIR), X-ray diffraction (XRD) and scanning electron microscopy (SEM). (C) 2016 Elsevier Ltd. All rights reserved.