Polymer nanocomposites exhibit complex behaviour due to physical and possibly also chemical interactions between individual components (polymer, clay, compatibilizer). Despite research and development of this material class has been done almost over 40 years (Toyota invented first polyamide-clay nanocomposite at 1985), there is still huge potential open due to difficulties coming from nanoparticles dispersion state in different polymers. This includes on one hand control of the compounding process and on other hand a proper characterization of nanoparticles dispersion in final material structure. In this lecture, advances in the mixing technology as well as characterization techniques will be shown on examples of polymer-clay nanocomposites, based on both synthetic and biopolymers. Concerning compounding process, results on laboratory as well on semi-industrial scale will be presented and relevant advantages and disadvantages will be discussed. From the point of view different characterization techniques, conventional (like mechanical and morphological testing) as well as advanced (rheology and spectroscopy performed off- and on-line) measurement approaches will be introduced.