Voltammetric techniques are usually employed for characterization of PEM single cells in terms of fuel crossover and electrochemical active surface. These techniques are, however, no more valid for individual characterization of the cells forming a PEM stack. Previous works suggested the use of chronopotentiometric measurements with current pulses: various interpretations of the curves can be used for characterization of individual cells, with, however, different accuracy levels in the determination of the two above cell features. The present manuscript establishes the comparison of voltammetric and potentiometric techniques for characterization of three single cells of the same grade, then potentiometric measurements were carried out with the stack formed by the above cells. Interpretation conducted by differential capacity plots was shown to lead to accurate characterization of electrochemical features of the three cells as indicated by the agreement between voltammetric and potentiometric techniques for individual cells and the data obtained in the stack.