Abstract: A process for treating a cellulosic material comprising extracting hemicellulose from the cellulosic material with an extractant comprising a cellulose solvent and a co-solvent to selectively extract hemicellulose therefrom and separating the extracted hemicellulose to form a cellulosic product comprising less hemicellulose than the cellulosic material. The extractant comprises a cellulose solvent and a co-solvent. The cellulose solvent is selected from the group consisting of an ionic liquid, an amine oxide and combinations thereof, and the co-solvent may preferably have a boiling point less than 120° C., or less than 100° C. The cellulosic product advantageously retains its cellulosic fiber morphology. The processes involve separating and recovering the hemicellulose and separating and recycling various process streams employed in the process.