The goal of this work is to evaluate the effect of the degradation of the components of a hybrid battery-fuel cell power unit on the operation of a train using hydrogen as its fuel. To this aim, it was decided to create a program written in the MATLAB environment that takes into account both fuel cell and battery degradation, and that allows to evaluate at every moment in the operating life of the train the state of aging of the two components of the power train, while tracing its impact on fuel consumption. The analysis is applied to a real case of a hybrid hydrogen train running on the Brescia-Iseo-Edolo line, a mountainous line located in northern Italy.