This presentation will introduce the audiences in cellulose nanocomposites and their manufacturing processing, also some possible applications areas will be discussed. The main difficulty, when producing cellulose-based nanocomposites, is to disperse the nanocellulose in the polymer matrix without degradation the polymer or the nanocellulose. Therefore the most common way to prepare cellulose nanocomposites have been solvent casting, where nanofibers or crystals are first dispersed the in a solvent and then mixed with a dissolved polymer or to prepare a “cellulose nanopaper” and impregnate that with a polymer resin. This presentation is dealing with extrusion and about the possible ways to disperse cellulose nanofibers or nanocrystals in a melt polymer. Challenges as well as pros and cons of different processing routes; 1) liquid feeding of the nanomaterials into the extruder and 2) dry feeding of nanomaterials will be discussed. Also some recently published studies on solid-state dispersion and cellulose nanofiber fibrillation using an extruder will be discussed. The main interest is to produce nanocomposites with well dispersed nanocelluloses, with improved properties, and at the same time develop an energy efficient and cost effective processing method, which can be up-scaled in industrial level.