Four years ago, the European Community project LIRES (Development of Light Water Reactor Reference Electrodes) was started with the objec- tive of developing high temperature reference electrodes for light water reactors (LWRs). To conclude this research project, a one-day seminar was organized with the topic: ‘High Temperature Electrochemistry in Light Water Reactors’ (EFC event No. 279, 30 November 2004, KU Leuven, Belgium). The objective of the seminar was to give an overview of the developments of electrochemical methods and techniques for use in high temperature, high pressure aqueous environments in Europe and to focus on their application to LWRs. This volume publishes the fruits of all the technical and scientifi c discussions which occurred during the friendly one- day seminar, including a selection of papers presented during this seminar and papers presented during EUROCORR conferences. These papers have been brought together as they all concern corrosion problems in LWRs, attempting to solve them using electrochemical methods.