Lignocellulosic biomass was hydrolyzed by combining an acidic ionic liquid, 1-(1-butylsulfonic)-3-methylimidazolium hydrogen sulfate, and microwave heating, resulting in high glucose yields and short reaction times. This new approach achieved 40% glucose yield from bagasse within 12 min at 160 degrees C; whereas, almost no glucose was yielded with a well-known method involving H2SO4 and conventional heating within 30 min at the same temperature. It was confirmed that the reaction temperature significantly affected glucose yield and reaction rate; whereas, the concentration of the acidic ionic liquid only affected the reaction rate. Three kinds of lignocellulosic biomass, including bagasse (herbaceous biomass), eucalyptus (hardwood), and Japanese cedar (softwood), were examined. Glucose yield was in the range of 30-40%, indicating that the present method effectively hydrolyzes various kinds of lignocellulosic biomasses.