In recent years, the impact of humans on the environment has been the subject of much debate. Car companies in particular are among the main actors in this environmental degradation with the polluting aspect of combustion cars. However, in recent years, these companies have started to switch to electric cars in order to reduce their impact on the environment. This is the case for Volvo, for example, where electrification is a priority. With the goal of becoming a climate neutral company by 2040, Volvo is driving innovation to reduce the use of polluting materials, such as oil.  Oil is not only used to power cars, but also in the fluids used to cool electrical machines or lubricate transmissions. However, alternatives to these fluids have emerged in recent years, such as glycerol-based or water-based lubricants. This Master Thesis aims to follow the evolution of water-based lubricants, but also to compare the performance of existing fluids within electric drivelines.  Water is known to have very good thermal properties but also to have a high electrical conductivity, which represents a big challenge for the use of this type of lubricant within an electric machine. It is with the aim of evaluating the impact of these properties that the following study investigates the electrical compatibility of a water-based lubricant within an electrical machine. The thermal performance of this type of fluid is also investigated and compared to that of an oil- based fluid also studied at Volvo. This master thesis will serve as a springboard for further studies of these lubricants, and will also raise questions and challenges that need to be addressed in the future in order to be able to take full advantage of the properties of these water-based lubricants.