In this work, a selective two-stage hydrolysis of lignocelluloses from corn stalk was developed through pH adjustment in 1-n-butyl-3-methylimidazolium chloride ([C4mim]Cl). In the first stage, the ligninhemicelluloses matrix of corn stalk was disrupted and hydrolyzed in the ionic liquid at pH 4.5 and 90 degrees C to obtain xylose with 23.1% yield. In the second stage, cellulose-rich materials in solid residues were further hydrolyzed in the ionic liquid at pH 23 and 90 degrees C to produce glucose with 26.9% yield, and pure lignin was also obtained. Structures of the hydrolysates were identified by 13C NMR and IR spectrum analysis, and the ionic liquid was recycled throughout the process. It is expected that the information provided here would be useful for the development of new methods to selectively produce monosaccharides from catalytic hydrolysis processes of biomass. (c) 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013