In order to tackle climate change, to increase energy supply security and to foster the sustainability and competitiveness of the European economy, the EU has made the transition to a low-carbon economy a central policy priority. This report builds on the first study conducted by the JRC in 2011 (Critical Metals in Strategic Energy Technologies), where critical metals were identified, which could become a bottleneck to the supply-chain of the low-carbon energy technologies addressed by the Strategic Energy Technology Plan (SET-Plan), namely: wind, solar (both PV and CSP), CCS, nuclear fission, bioenergy and the electricity grid. Fourteen metals were identified to be a cause for concern. After taking into account market and geopolitical parameters, five metals were labelled ‘critical’, namely: tellurium, indium, gallium, neodymium and dysprosium. The potential supply chain constraints for these materials were most applicable to the deployment of wind and PV energy technologies.