NOVELTY - Hydrolyzing lignocellulosic biomass material, comprises: loading step comprising introducing the lignocellulosic biomass material and an enzyme composition into a reactor; mixing step comprising stirring or agitating the content of the reactor so that the enzyme composition and the lignocellulosic biomass material are sufficiently mixed into a substantially homogenous slurry that is a saccharification mixture; and saccharification step comprising incubating the saccharification mixture under conditions that allow the hydrolysis of biomass materials into soluble fermentable sugars.    USE - The method is useful for hydrolyzing a lignocellulosic biomass material to produce soluble fermentable sugars (claimed) that are used to produce high value chemicals and fuels.    ADVANTAGE - The method exhibits improved hydrolysis efficacy and/or efficiency, and provides improved yields of fermentable sugars, in an economical manner, by utilizing abundantly available and inexpensive lignocellulosic biomass material and maintaining desired dissolved oxygen level in the saccharification mixture and throughout the saccharification step.    DETAILED DESCRIPTION - Hydrolyzing a lignocellulosic biomass material, comprises: a loading step comprising introducing the lignocellulosic biomass material and an enzyme composition into a reactor; a mixing step comprising stirring or agitating the content of the reactor so that the enzyme composition and the lignocellulosic biomass material are sufficiently mixed into a substantially homogenous slurry that is a saccharification mixture; and a saccharification step comprising incubating the saccharification mixture under conditions that allow the hydrolysis of biomass materials into soluble fermentable sugars, where the level of dissolved oxygen in the saccharification mixture is maintained at a level of above 1.5% of the saturation dissolved oxygen level during the saccharification step. An INDEPENDENT CLAIM is also included for an apparatus for carrying out the lignocellulosic biomass enzymatic hydrolysis process, comprising a gas inlet, and a dissolved oxygen probe.