Cool materials keep the roof cool under the sun by reflecting the solar radiation away from the building and radiating the stored heat away during night time. The potential of the technology is very promising at EU level and, in particular, in the Mediterranean area. EU supports the Cool Roofs Project, where important technical actions are developed. The technical and scientific activities include: development of the first EU cool materials database; implementation of five case studies with different building typologies equipped with different cool materials; development and validation of a dedicated toolkit; production of the cool materials handbook. The paper summarises the most significant results achieved in the project.