Abstract: Cellulose-containing material is rapidly saccharified to convert pentosans and hexosans to sugars by cooking under pressure at from 180.degree. C. to 220.degree. C. with acetone-water solvent mixture carrying from 0.05 to 0.25 weight percent of phosphoric, sulfuric or hydrochloric acids.A predominantly cellulosic material, e.g. a delignified pulp, is hydrolysed to yield relatively pure glucose recoverable from liquor which is flowed through the cellulose, then withdrawn and cooled and neutralized within an elapsed time of a minute or less.Whole wood is nearly totally dissolvable by the process, yielding mixed pentoses and hexoses. The dehydration and degradation products of sugars are formed by prolonging retention time of liquor from 20 to 45 minutes.