Written to assist individuals in academia and industry and in relevant regulatory and policy roles, this publication provides a summary of the current knowledge on the status of research, technological developments, reactor designs and experiments in the area of advanced reactors that are fuelled or cooled by a molten salt. Identification of challenges and areas where research and development are still required in preparation for commercial deployment gives context to current and planned work. The aim of this publication is to share information on programmes and projects on molten salt reactors in Member States which will shape future collaborative efforts.