The Hy2Rail project in Austria focuses on exploring the conversion of existing rail vehicles to a more environmentally friendly option by replacing diesel engines with a hydrogen battery hybrid drive. The project, part of the 'Mobility of the Future' program, converted diesel-hydraulic universal locomotives and developed a technology demonstrator from a diesel-electric motor tower car. The conversion involved incorporating a fuel cell system developed by m.ZERO and lithium-nickel-manganese-cobalt batteries, providing the demonstrator with a range of approximately 450 km. Additionally, the project included the creation of a mobile emission-free on-site generator, hydrogen refueling system, and a simulation suite programmed by the University of Rome, Tor Vergata for the battery and fuel cell hybrid system. Various partners collaborated on different aspects of the project, ensuring a comprehensive approach to eco-friendly rail technology. The demonstrator operates as a true hybrid vehicle, allowing for efficient energy usage by utilizing both the fuel cell system and the battery for traction, with the ability to operate them together if needed. This innovative approach showcases the potential for converting existing rail vehicles to eco-friendly alternatives, contributing to sustainability and emission-free rail transport.