Redox behavior of electronically conducting polymers (ECPs) and inorganic active metal oxides intercalation electrodes (IEs) were analyzed by using Frumkin-type intercalation isotherms. Using such isotherms appears to be very useful in fast screening and classification of various electroactive materials. It provides a clear tool for linking the equilibrium properties of these materials to their dynamic (transport) characteristics. In this article, we review and discuss the common features of these materials with distinctions between micro- and macrostructures, including host expansion, distortion and structural transitions; ions and solvent permeation (partioning) into the hosts; conformational flexibility and morphological changes; ordering and energetic dispersion of sites; electronic and ionic conductivity, etc.; and the ways in which these structural aspects may affect their redox behavior. (C) 2004 Elsevier Ltd. All rights reserved.