Effectively overcoming the recalcitrance of lignocellulosic materials is one of the largest technical obstacles to the production of chemicals and bioethanol from the most abundant renewable bioresource -- lignocellulose. A novel concentrated phosphoric acid/acetone lignocellulose fractionation for corn stover has been developed recently. This new technology has four distinctive features: modest reaction conditions (~50oC and atmospheric pressure); fractionation of lignocellulose into amorphous cellulose, hemicellulose sugars, lignin, and acetic acid; generation of highly reactive amorphous cellulose; and cost-effective reagent recycling. Here we will present the latest progress on this technology applicable to other lignocellulosic materials such as switchgrass, hybrid poplar (hardwood), and Douglas fir (softwood).