The objective of this report is to review the relevant information on a brominated flame retardant hexabromocyclododecane (HBCDD) in relation to the screening criteria of the Stockholm Convention on Persistent Organic Pollutants (POPs) and of the Protocol on Persistent Organic Pollutants of the UNECE Convention on Long-Range Transboundary Air Pollution for adding new substances to these instruments. Some additional information needed in the consideration of the possible nomination of the substance as a new POP is also provided. This joint Nordic project has been prepared by consultant Johanna Peltola-Thies and supervised by a project group under Bjørg Fjeld from the Norwegian Pollution Control Authority. The project was financed by the Nordic Council of Ministers through the Nordic Chemicals Group and the Nordic Sea and Air Quality Group.