Systematic electrochemical research on the redox properties of conjugative 7rsystems has been carried out since the mid-1950s beginning with the pioneering work of Hoijtink [l]. He showed that the cathodic reduction of olefinic and aromatic 7r-systems is energetically facilitated when the 7r-system is extended by introducing additional aromatic units or conjugated double bonds.Very reliable linear correlations between the reduction potentials and molecular orbital energies of a series of aromatic hydrocarbons and diphenylpolyenes were one of the first successful applications of the Huckel molecular orbital theory (HMO) and allowed the development of a coherent picture of redox processes. Hoijtink et al. had already noticed that most aromatics and polyenes can be further reduced to their respective dianions. Although at the time all the measured dianion potentials were influenced by follow-up processes, it became obvious that their positions also shift to less negative values for larger 7r-systems. Moreover, in the case of 1 ,n-diarylpolyenes it was observed that the separation between the first and the second redox step diminished as a function of the polyenic chain length [2, 3 , 41. Later on, progress in electrochemical instrumentation and techniques [5, 61 facilitated the generation and study of multiple-charged anionic and cationic species. Thus, Hammerich and Parker [7,8] were able to generate persistent diions of numerous aromatic systems in cyclic voltammetric experiments. Hunig and coworkers [9] showed that chain-like oligovinylene systems with electroactive end groups, may, in principle, undergo reversible two step redox processes, and that the separation between the two redox potentials diminishes drastically with an increasing number of vinylene groups.The discovery of the redox properties of conducting polymers in 1979 gave new impetus to the electrochemistry of conjugated organic systems, initiating extended studies on the charge storage characteristics of these species. However, at the beginning of this research electrochemists preferred to focus attention on polymeric materials, largely neglecting all the experience gained in the characterization of monomeric or oligomeric species. Only two independent studies by Diaz [lo] and Bredas [ I l l pointed out that, in agreement with the previous results of Hoijtink [2], the oxidation and reduction onsets in chain-like conjugated oligomers are dependent on the chain length and shift linearly to lower energies with the inverse number of aromatic units or double bonds. For the rest, the interpretation of electrochemical data was determinated by experimental results and theories obtained from solid state physics and macromolecular chemistry.As a consequence of this view the bipolaron model was applied to conducting polymers [12, 131. It ideally assumes during the charging process the formation of