To improve the reducing sugar production from catalpa sawdust, thermo-chemical pretreatments were examined and the chemicals used including NaOH, Ca(OH)(2), H2SO4, and HCl. The hemicellulose solubilization and cellulose crystallinity index (CrI) were significantly increased after thermo-alkaline pretreatments, and the thermo-Ca(OH)(2) pretreatment showed the best improvement for reducing sugar production comparing to other three pretreatments. The conditions of thermo-Ca(OH)(2) pretreatment and enzymatic hydrolysis were systematically optimized. Under the optimal conditions, the reducing sugar yield increased by 1185.7% comparing to the control. This study indicates that the thermo-Ca(OH)(2) pretreatment is ideal for the saccharification of catalpa sawdust and that catalpa sawdust is a promising raw material for biofuel. (C) 2016 Elsevier Ltd. All rights reserved.