This book presents themes such as fuel cell electro-catalysis and membrane development as well as durability of fuel cell components. It presents varying results and views on a fundamentally interesting method, broad-band dielectric spectroscopy, of particular interest because of the high potential for insight arising from the method on the one hand coupled to radically different interpretations of data in the literature. In short, the debate is over matters of interpretation of features in the data. Application of dielectric spectroscopy to the study of polymers has a long history. However, polymeric electrolytes with substantial conductivity present significant problems for traditional measurement techniques using low surface area electrodes. Significant interfacial polarization can arise in such cases, leading to spectral features that are spurious.