Abstract Research on clay-based polymer nanocomposites (CPN) is a field of increasing interest from many different points of view that are not exclusively directed towards improving mechanical properties of plastic materials. Rather, significant interest lies also in systems containing functionalities such as electrical conductivity, insulating capacity, membrane effects, corrosion protection or fire retardant behavior ( Pinnavaia and Beall, 2000 ; Ruiz-Hitzky and Van Meerbeek, 2006 ). Among these, CPN that contain electroactive polymers with electronic conductivity, such as polyaniline (PANI) and polypyrrole (PPy), or an ability to facilitate ion-mobility, such as poly(ethylene oxide) (PEO), or the ability to generate conducting carbons, such as polyacrylonitrile (PAN), are especially attractive. This is because of their potential applications as components in various electrochemical devices such as solid-state batteries, fuel cells and modified electrodes ( Ruiz-Hitzky and Aranda, 2000 , Ruiz-Hitzky et al. , 2004 ; Aranda et al. , 2006 ). Since PPy-FeOCl nanocomposites showing electronic conductivity were first reported by Kanatzidis et al. (1986) , a large family of polymer-inorganic solid nanocomposites based on layered inorganic hosts has been prepared. The variety of hosts includes those built-up of uncharged layers, positively or negatively charged layers, and containing insulator, semiconductor, superconductor, or redox properties. These in combination with a variety of electroactive polymers prepared via different synthetic routes are discussed below and summarized in Figure 1 ( Ruiz-Hitzky, 1993 ; Ruiz-Hitzky and Aranda, 1997 ; Ruiz-Hitzky et al. , 2006 ). One might presume that the insulator character of clay