Improving the efficiency of the use of critical and valuable materials is a general target in the European Union, due to their importance for the industry, price fluctuations and supply risks. The use of secondary raw material and recycling was recommended to the European Commission as a strategy to reduce and alleviate the supply risks facing critical raw materials. The EU Raw Materials Initiative has led, through the European Innovation Partnership (EIP), to the definition of research and innovation actions to mitigate these risks. The Strategic Implementation Plan (SIP) of these research and actions includes the building up of the EU raw materials knowledge base. Our ProSUM project intends to supply the inventory component of this knowledge base. Data on primary and secondary raw materials are available in Europe but it is scattered amongst a variety of institutions including government agencies, universities, NGOs and industry. The data are often stored in databases with their own design and architecture making it difficult and time consuming to merge or compile. Moreover, where data relates to the composition of waste, different and, often incomplete, sampling and analytical approaches may have been used which makes it challenging to aggregate and compare data. The diversity of products, with for example over 660 identified product types for EEE, with changing compositions over time and sometimes rapidly change technologies and market demands makes the prospecting of secondary CRMs and valuable materials in the ‘urban mine’ difficult to quantify. Moreover, limited collection of products for WEEE, ELV and Batteries due to disposal along other solid wastes to incineration and landfill, due to exports (for reuse) and due to hibernation in for instance homes is limiting recovery potential of CRMs. According to UNEP (2013): “Quantification of the urban ore body – The quantification of the metals contained in this stock, their locations and fate in waste flows is crucial to allow for high recovery rates and a prerequisite to support decisions on R&D activities and investments in metal recycling infrastructure and technologies. In this context policies should be developed based on geological approaches known from primary metallurgy” The ProSUM project chooses the four most relevant and challenging waste groups having the highest CRM content from all potential secondary sources in the ‘urban mine’ . For example, EEE, vehicles and batteries cover 99% of gallium consumption (integrated circuits and optoelectronic devices), 74% of indium (display panels) and 60% of tantalum (electrolytic capacitors). Rechargeable batteries are the main cobalt end-use sector (27%). 8% of the rare earths are used for batteries, 19% for magnets (in vehicles), 7% for phosphors and 1% for ceramics capacitors. The four waste groups (three ‘product groups’ plus ‘mining waste’) are: – End-of-Life Vehicles (ELV ) – Waste Electrical and Electronic Equipment (WEEE) – Spent batteries (Batteries) – Mining waste These four groups have particular challenges in monitoring, but at the same time offer opportunities in developing harmonised and standardised data, compliant with existing primary raw materials databases in order to provide a general architecture for an inventory for secondary raw material in the urban mine. Acknowledging the increasing number of initiatives, activities and EU and national-wide studies to collect and collate data, this challenge can only be overcome by bringing together an interdisciplinary consortium, through active coordination and support with all stakeholders in the value chain.