The main objective of this concerted action is to explore the need for, and to develop the structure and maintenance of a European thermodynamic database to be used primarily for the "validation" of geochemical models for the migration of radionuclides and other solutes from nuclear waste repositories. It is also useful for problems related to other contaminated areas. Within the scope of a Concerted Action we have reviewed ongoing thermodynamic database activities (aqueous and pure substance databases) and also specific areas where the current thermodynamic data are non-existent, or of poor quality. We have identified some of the additional experimental work that is judged necessary and indicated areas where the database can rely on existing thermodynamic information. Finally, and perhaps most importantly, we have looked into the structure of ongoing research into nuclear waste management and related areas within Europe. Continued strong support to the European institutes where cutting-edge research on radio- and nuclear chemistry, including actinide chemistry is taking place, is essential because few universities have the capacity to tackle such problems. Through a "mobility" programme, these centres will be able to provide the training and research facilities for young university students. A number of research projects suitable for diploma or thesis work are identified in the final JETDEM report. In addition to specialised disciplinary training, the programme outlined will provide young scientists and other participants with the broader perspective required to solve nuclear waste disposal problems.