The ProSUM Metadata Catalogue is the central access point to metadata concerning data on secondary sources of raw materials from “urban mines” - data on WEEE, ELVs, batteries and mining waste. It provides tools for compilation of those metadata in a standardized format that will allow users to effectively search through the database. In order to make the data discoverable in the most efficient way, the catalogue is fully compliant with international standards and supports the distributed system of metadata administration. Only digital and structured information (non-geographic and spatial datasets or dataset series and spatial data services - WMS, WFS) are described by metadata in this catalogue. In order to display a metadata record for which an on-line map service is available, the Metadata Catalogue will be integrated into the ProSUM Portal. The catalogue will enable systematic discovery, viewing and use of data on WEEE, ELVs, batteries and mining waste across Europe.