Cellulose is an important natural material used in many industrial applications, such as food and medicine. Cellulose micro-fibrils (CMF) are produced from wood, plants, and bacteria, where the cellulose is present in a highly aggregated state. The de-agglomeration process involves high shear deformations and addition of adsorbing polymer as a stabilizer. The effect of these actions on the microstructure is a key to understanding the overall process of CMF formation as well as establishing a link between macroscopic properties and microstructure of these materials. The samples will be dispersed in D2O and we are expecting to see the amorphous cellulose shell of the micro-fibrils to be saturated by D2O, whereas the crystalline core of micro-fibrils will stay unchanged to create a high contrast. The SANS experiments will determine the effect of the process steps on the mesostructure.