The decommissioning of nuclear power plants is a topic of increasing interest to governments and the industry as many nuclear units approach retirement. It is important in this context to assess decommissioning costs and to ensure that adequate funds are set aside to meet future financial liabilities arising after nuclear power plants are shut down. Furthermore, understanding how national policies and industrial strategies affect those costs is essential for ensuring the overall economic effectiveness of the nuclear energy sector. This report, based upon data provided by 26 countries and analysed by government and industry experts, covers a variety of reactor types and sizes. The findings on decommissioning cost elements and driving factors in their variance will be of interest to analysts and policy makers in the nuclear energy field.