Sugarcane bagasse pretreated by combining O-2 and NaOH with different variables was conducted to improve its enzymatic digestibility and sugar recovery, and the results were compared with sole NaOH pretreatment. Lignin removal for O-2-NaOH pretreatment was around 10% higher than that for sole NaOH pretreatment under the same conditions, and O-2-NaOH pretreatment resulted in higher glucan recovery in the solid remain. Subsequently, O-2-NaOH pretreated sugarcane bagasse presented more efficient enzymatic digestibility than sole NaOH pretreatment. Under the moderate pretreatment conditions of combining 1% NaOH and 0.5 MPa O-2 at 80 degrees C for 120 min, a high glucan conversion of 95% was achieved after 48 h enzymatic hydrolysis. Coupled with the operations of pretreatment and enzymatic hydrolysis, an admirable total sugar recovery of 89% (glucose recovery of 93% and xylose recovery of 84%) was obtained. The susceptibility of the substrates to enzymatic digestibility was explained by their physical and chemical characteristics. (C) 2016 Elsevier Ltd. All rights reserved.