Decommissioning is the final phase in the life cycle of an installation. The term decommissioning refers to administrative and technical actions taken to allow removal of some or all of the regulatory controls from a nuclear facility. It is an integral process that involves complex and diverse operations as well as several stakeholders and regulatory organisations. Regardless of its complexity and its cost, suitable strategies and techniques for the decommissioning of nuclear power plants are available, and have been successfully applied in many sites. However, the operative experience could be better collected, and the lessons learned should be shared as their equivalents of the operational phase. This is a major issue considering the large number of NPP that are in this phase, or are close to their shutdown. This Summary Report presents the results of a study performed by the European Clearinghouse on Operating Experience Feedback of NPP about events related to decommissioning.