Process for increasing the enzymatic accessibility of a thermally treated ligno-cellulosic biomass feedstock

It is disclosed a process for increasing the enzymatic accessibility of a thermally treated ligno-cellulosic biomass feedstock which has been thermally treated at a severity factor. The process comprises a step of fiber shives reduction， for reducing the amount of long shives. The thermally treated ligno-cellulosic biomass after fiber shives reduction is characterized by having an increased glucans accessibility and by forming a slurry having a low viscosity.