To support the development and monitoring of the EU Energy Technology Policy and under the umbrella of SETIS, the Joint Research Centre (JRC) of the European Commission (EC) needed a comprehensive ocean energy technology database, containing information on technologies that have been tested in real water conditions. A few open access and private databases on ocean energy have been built over the last decade. However, to best suit its needs, the JRC commissioned its own, with a similar level of detail as its other databases on more mature technologies (e.g. wind energy). The database was built using ACCESS and contains detailed information in 4 main groups which are interlinked: 1) technical descriptions of device technology, 2) commercial information of the developer, 3) project information such as number of units, costs, capacity, layout, type of moorings/foundations and 4) site characteristics such as resource levels. One of the main focuses on the database definition phase was the characterization of wave and tidal devices by their sub-assemblies and components, and how these correlate. Standard classifications of devices regarding their conversion method, operation method, and moorings & foundations have been used. The database was firstly filled in using available public information, from technical specifications to speciality reports. After that first step, developers were contacted to validate and complete the information, ensuring that the JRC has the most reliable and up to date information to support decision making. This paper looks into the process of developing this database, focusing on the choices of characterizing the devices by their functional components and/or sub-assemblies. An example state of the art analysis is provided to show its functionalities.