This lecture will present chemical routes designed for the large scale production of functional, redispersible cellulose nanofibrils (CNF) with applications in the field of adhesives, packaging and textiles. Suspensions of CNF obtained by mechanical disintegration and homogenization of pulps from bleached beech, wheat straw and oat were chemically surface-treated (e.g. silane condensation, etherification, oxidation reactions) prior to drying. This facilitates redispersion of the CNF in polymer matrices, organic or non-organic solvents showing the same network formation as native CNF suspensions. Also, treated CNF are carriers of functional groups (COOH, NH2) which are amenable to further chemical modification (e.g. by cross linking with biopolymers like PLA). The chemically modified CNF were characterized by spectroscopic (NMR, FT-IR, XPS) and morphological (SEM-EDX) methods. Also, the mechanical performance of resulting nanocomposites (CNF embedded in a model polymer matrix) was evaluated by mechanical (universal tensile tests) and dynamic mechanical analysis (DMA).