Wiener Linien, in collaboration with Hyundai and Slovenian manufacturer TAM, is testing a new demo fuel cell bus in Vienna. The vehicle, featuring 700-bar hydrogen storage technology, is the first of its kind in Europe. Powered by a fuel cell generating 90 kW of energy and a 180 kW electric motor, the bus produces zero greenhouse gas emissions. Wiener Linien's hydrogen bus initiative is supported by EU funding and aims to develop sustainable urban transport solutions. The bus will be refuelled at Wiener Linien's hydrogen filling station in Leopoldau, which supports both 350- and 700-bar refuelling. This initiative is part of a broader effort by Wiener Stadtwerke, Wiener Netze, and Wien Energie to promote environmentally friendly transportation. Future plans include deploying ten hydrogen buses from CaetanoBus and ten hydrogen minibuses from Rampini, replacing older electric buses. The hydrogen for these vehicles is produced in Vienna from renewable energies, ensuring emission-free transportation. The project demonstrates a commitment to reducing environmental impact and advancing sustainable mobility in Vienna.