The International Fusion Materials Irradiation Facility - Demo Oriented NEutron Source (IFMIF-DONES) is a novel Research Infrastructure based on a unique neutron source with energy spectrum and flux tuned to those expected for the first wall in future fusion reactors, to investigate radiation damage phenomena and to characterize materials irradiated under such conditions. It will also develop a unique high-current high duty-cycle accelerator technology, liquid metal target technology and advanced control systems. Since 2007, the original IFMIF project has been pursued by Japan and the European Union under the Broader Approach Agreement in the field of fusion energy research and in December 2017 Fusion for Energy (F4E)positively evaluated the Spain-Croatia joint proposal to site DONES in Granada (Spain) and at this moment a wide international collaboration is being fostered to design and build the facility. The primary goal of the IFMIF-DONES Preparatory Phase project is to elaborate and draft the consortium agreement allowing for the construction of the facility. During the Preparatory Phase, the Project will deal with the financial, legal and organisational issues related to the international character of the facility during its construction and operation phases. The Preparatory Phase is also the ideal framework to attract other partners, also to ensure the operation and exploitation of the project, such as the already confirmed Andalucía Region Authority and the Spanish Government, EUROfusion and F4E that cover about 75 % of construction costs.