Electric vehicles, equipped with electrochemical batteries, are expected to significantly penetrate the automotive market in the next few years. Though, the recharge time for battery pack and the autonomy range can constitute a limit. An appropriate use of fuel cell technology in electric vehicles can now represent an advantageous choice both from a technical and economic point of view. This paper reports the results of the development of a hybrid electric city bus, performed by the synergy between fuel cell and batteries. A pure electric city bus, equipped with eight Zebra batteries, was acquired and modified in a fuel cell and batteries hybrid vehicle. In the final version the bus was equipped with six batteries and a hydrogen plant with a proton exchange membrane fuel cell system. In particular an innovative powertrain management, where even the time required for the terminal stops is used to charge the batteries by the fuel cell, is described. Set-up tests on the fuel cell system acquired are presented. Further, tests were conducted also on the battery pack working on board in a real route to demonstrate the capability of the reduced battery pack to drive the vehicle.