Efficient pretreatment is essential for economic conversion of lignocellulosic feedstocks into monosaccharides for biofuel production. To realize high sugar yields with low inhibitor concentrations, hot water or dilute acid pretreatment followed by disk milling is proposed. Corn stover at 20% solids was pretreated with hot water at 160-200 degrees C for 4-8 min with and without subsequent milling. Hot water pretreatment and disk milling acted synergistically to improve glucose and xylose yields by 89% and 134%, respectively, compared to hot water pretreatment alone. Hot water pretreated (180 degrees C for 4 min) and milled samples had the highest glucose and xylose yields among all hot water pretreated and milled samples, which were comparable to samples pretreated with 0.55% dilute acid at 160 degrees C for 4 min. However, samples pretreated with 1% dilute acid at 150 degrees C for 4 min and disk milled had the highest observed glucose (87.3%) and xylose yields (83.4%). (C) 2016 The Authors. Published by Elsevier Ltd.