In the present contribution an experimental validation and a measurement routine of a new electrochemical method to study dynamics of electrochemical processes, the so-called concentration alternating frequency response analysis (cFRA) is presented. In cFRA the electrical response of the cell (current or potential) to periodic perturbation of specific reactant feeds is studied by means of linear system analysis. For the example of a polymer electrolyte fuel cell (PEMFC) we show that cFRA, in contrast to classical electrochemical impedance spectroscopy (EIS), detects selectively the effect of the dynamics of mass transport of reactants and products inside the different layers of the PEMFC. Moreover, cFRA can be used to diagnose the humidification state of the fuel cell cathode. Finally, procedures to improve the diagnostic skills of the proposed cFRA technique are discussed and directions of future work are recommended.