This research is focused on the assessment of running properties of a rail multiple unit (MU), which an original diesel powertrain has been changed by a hydrogen powertrain. There are analysed the output quantities in a wheel/rail contact and their influence to running safety. A rail MU is evaluated, which is produced by a commercial manufactured and with newly designed powertrain includes hydrogen fuel cells. This modification of the solved MU means a significant change of its structure. The vehicle itself consists of three articles. The changes mainly related with the position of a centre of gravity of individual articles, their masses as well as moments of inertia. The research has been conducted in a commercial multibody software Simpack. A multibody model of the solved MU consists of rigid bodies and other modelling elements. A real railway track section in Slovakia has been chosen for simulation computations. Based on the findings and obtained results, the modified MU equipped with the hydrogen powertrain operation is within the valid safety criteria. However, the reached axleload of this vehicle does not meet the required values.