The Nuclear Energy Agency (NEA) Working Party on Technical, Environmental and Safety Aspects of Decommissioning and Legacy Management (WPTES) is organising an international workshop on Innovative Techniques and Technologies to Support Characterisation and Decommissioning of Complex and Legacy Sites. Topics will include innovative site and radiological characterisation, as well as decommissioning techniques and technologies. The workshop will also provide information on application of existing technologies to new problems including lessons learned and best practices to overcome the challenges associated with the use of existing technologies. The workshop will gather implementers, representatives from government and regulatory agencies, researchers and other stakeholders involved in decommissioning of complex and legacy sites. As regulators will be part of the workshop audience, presentations on regulatory concerns and perspectives should be included.