The increasing interest in the use of electrical techniques for the characterisation of material properties indicates the need for a book in which the most important issues in this area are addressed. Consequently, the aim of this volume is to provide a comprehensive description of the electrical techniques used in studies of the semiconducting properties of materials based upon ionic solids, principally metal oxides. A second aim is to present an updated review of the most important data on the defect-related properties of ionic solids, such as the transport of charge or matter, and their electrochemistry in an accessible form.