The Joint Research Centre (JRC) of the European Commission develops certified matrix reference materials for laboratory diagnostics, environmental and food analytics, as well as industrial quality control. We offer a wide range of materials, from nanomaterials to fine dust for air quality monitoring, from heavy metals in human blood to markers for coeliac disease in serum, from food products to help fighting food fraud to toxins in food. Our certificates clearly specify traceability and uncertainty of the certified values. In the certification report for each certified reference material (CRM), the material processing, homogeneity, stability and characterisation studies are described. All CRMs are produced according to the ISO 17034 accredited quality system.