Due to the environmental problems associated with fossil fuels and a big need from the market, the majority of the automotive industry is going towards fully electric vehicles (EVs). To further reduce the environmental footprint there is ongoing research on the use of fossil-free lubricants, if they could be used to lubricate the drive train which could further reduce the use of fossil oil in the automotive industry. These lubricants have also been shown to have lower friction and could thus increase the efficiency of the transmission and therefore the driving range. To ensure the performance and reliability of these new lubricants they need to be evaluated and tested in monitored environments. This master thesis is about designing a gear test rig to test and evaluate the efficiency, reliability and wear rate of new types of fossil-free lubricants such as water-based lubricants (WBL) for use in electric vehicle gear transmissions. By first doing an external analysis of current solutions for gear test rigs, and having discussions with researchers at the university and competent people in the industry, product requirements were set. Then by following Ulrich, Eppinger & Yang's product development process concepts could be found and evaluated until a final concept was further developed. After dimensioning and specifications of the sub-systems, a detail-designed test rig and proposal on solutions could be delivered with a list of components and suppliers.