Solid-state electrochemical devices, such as batteries, fuel cells, membranes, and sensors, are becoming pervasive in our technologically driven lifestyles. The development of these devices involves common research themes such as ion transport, interfacial phenomena, and device design and performance, regardless of the class of materials or whether the solid state is amorphous or crystalline. However, results of recent research in this field tend to be presented in symposia separated along the lines of particular solidstate materials disciplines rather than by phenomena controlling device performance. The papers in this issue of ECS Transactions were presented at the fifth of a series in international symposia "Solid-State Ionic Devices V", at the 212th Electrochemical Society Meeting, in Washington DC, October 7-12, 2007. The intent of the symposia was to provide a forum for current advances in ionically conducting materials and devices that is organized along phenomenological lines, rather than by specific material discipline. The papers in this issue range from the fundamentals of ionic and mixed ionic-electronic transport to device performance and are in keeping with that intent.

Solid-state electrochemical devices, such as batteries, fuel cells, membranes, and sensors, are critical components of technologically advanced societies in the 21st Century and beyond. The development of these devices involves common research themes such as ion transport, interfacial phenomena, and device design and performance, regardless of the class of materials or whether the solid state is amorphous or crystalline. The intent of this international symposia series is to provide a forum for recent advances in solid-state ion conducting materials and the design, fabrication, and performance of devices that utilize them. The papers in this issue of ECS Transactions were presented at the 6th Solid State Ionic Devices symposium, at the 214th meeting of The Electrochemical Society, October 12-17, 2008 in Honolulu, Hawaii.

The papers included in this issue of ECS Transactions were originally presented in the symposium "Solid State Ionic Devices 8 - NEMCA", held during the 218th meeting of The Electrochemical Society, in Las Vegas, Nevada from October 10 to 15, 2010.

In recent years Solid State Ionics and Solid State Microbatteries have attracted considerable interest due to the important role which they may play in the future of microelectronics and eventually in other fields of energy storage. This volume presents papers on the theory, experiments and applications in this field including: Solid state microbatteries; Thin films solid state batteries; Fast ion conduction; Intercalation and lattice dynamics in layered materials; Electrochromes; Solid state diffusion; and Microsensors.