NOVELTY - Preparing hydrolysate of lignocellulosic biomass comprises: (a) providing lignocellulosic biomass having hemicellulose, cellulose and lignin; (b) transforming biomass into particulate material; (c) preparing slurry of particulate material in water; (d) contacting slurry with mixture of organic acid and mineral acid to form reaction mixture; (e) continuously introducing mixture into hydrolyser; (f) maintaining desired temperature and pressure in hydrolyser for desired time; (g) continuously withdrawing hydrolysate from hydrolyser; and (h) separating hydrolysate into liquid and solid streams.    USE - The process is useful for preparing hydrolysate of a lignocellulosic biomass, which is useful for obtaining glucose (claimed) or pentose sugars.    ADVANTAGE - The process: provides the hydrolysate, which contains total phenolic compounds of not greater than 6000 ppm and total furans of not greater than 1000 ppm (claimed), and provides sugars at a higher rate of conversion and yield; can be carried out at a lower temperature and pressure, hence reduces the production of toxic/inhibitory products; and provides the residual cellulose that is more amenable to enzymatic digestion by cellulases as compared with conventional methods.    DETAILED DESCRIPTION - Preparing hydrolysate of a lignocellulosic biomass comprises: (a) providing a lignocellulosic biomass having a hemicellulose, a cellulose and a lignin; (b) transforming the biomass into a particulate material; (c) preparing a slurry of particulate material in water; (d) contacting the slurry with a mixture of an organic acid and a mineral acid to create a reaction mixture; (e) continuously introducing the reaction mixture into a hydrolyser; (f) maintaining a desired temperature and pressure in the hydrolyser for a desired time to create a hydrolysate from the reaction mixture; (g) continuously withdrawing the hydrolysate from the hydrolyser; and (h) separating the hydrolysate into a liquid stream and a solid stream. INDEPENDENT CLAIMS are also included for:    (1) a liquid stream comprising xylose;    (2) a solid stream comprising residual cellulose; and    (3) a hydrolysate comprising at least four times more xylose than glucose, and residual cellulose for an enzymatic hydrolysis process to obtain glucose.