Abstract: High-shear, microcavitation is used to shred and disintegrate fibrous lignocellulose-containing biomass to make the biomass more susceptible to hydrolysis. This process is preferably performed with the biomass particles dispersed in a slurry created using only water. The process can be performed on slurries created with other liquids such as liquid ammonia, aqueous solutions of acid or alkali reagents, or enzyme solutions containing cellulase, cellobiase or a combination thereof. High-shear microcavitation is carried out by subjecting the slurry to high-shear forces by injecting the slurry cross-currently into a turbulent Couette flow created in a high-frequency, rotor-stator device. This microcavitation shatters the fibrous structure of the biomass in the slurry thereby creating a sheared slurry.