The key to the efficient transmission and conversion of low-carbon electrical energy is the improvement of power electronic devices. Diamond is considered to be the ultimate wide bandgap semiconductor material for applications in high power electronics due to its exceptional thermal and electronic properties. Two recent developments - the emergence of commercially available electronic grade single crystals and a scientific breakthrough in creating a MOS channel in diamond technology, have now opened new opportunities for the fabrication and commercialisation of diamond power transistors. These will result in substantial improvements in the performance of power electronic systems by offering higher blocking voltages, improved efficiency and reliability, as well as reduced thermal requirements thus opening the door to more efficient green electronic systems. These improvements are expected to increase the efficiency of power converters by a factor of 4, yielding a 75% reduction in losses. In this context, the objective of GreenDiamond is to fabricate a 10kV transistor in a high power package, followed by a high voltage AC/DC converter based on such devices. To meet GreenDiamond’s challenging goals, the consortium gathers experts on power device design, diamond growth and characterization, packaging and testing as well as an innovative end-user. Most of the partners are also involved in SiC or GaN technology, allowing the project to benefit from their ample experience and achievements in wide bandgap semiconductors. As far as diamond transistor structure is concerned, unlike GaN and SiC, Europe still has a significant scientific and technological advantage over non-EU competitors. It is therefore extremely important to maintain the competitive edge that will lead the development of truly green electronics in the near to medium term future.