Olive tree biomass (OTB) can be used for producing second generation bioethanol. In this work, extracted OTB was subjected to fractionation using a sequential acid/alkaline oxidative pretreatment. In the first acid stage, the effects of sulfuric acid concentration and reaction times at 130 degrees C were investigated. Up to 71% solubilization of hemicellulosic sugars was achieved under optimized conditions (2.4% H2SO4, 84 min). In the second stage, the influence of hydrogen peroxide concentration and process time were evaluated at 80 degrees C. Approximately 80% delignification was achieved under the best operational conditions (7% H2O2, 90 min) within the experimental range studied. This pretreatment produced a substrate with 72% cellulose that was highly accessible to enzymatic attack, yielding 82 g glucose/100 g glucose in delignified OTB. Ethanol production from both hemicellulosic sugars solubilized in the acid pretreatment and glucose from enzymatic hydrolysis of delignified OTB yielded 15 g ethanol/100 g OTB. (C) 2017 Elsevier Ltd. All rights reserved.