In designing and controlling fuel cell systems it is advantageous having models predicting fuel cell behavior in steady-state as well as in dynamic operation. This work examines the use of Electro-chemical Impedance Spectroscopy (EIS) for characterizing and developing an impedance model for a high temperature PEM (HTPEM) fuel cell stack. A Labview virtual instrument has been developed to perform the signal generation and data acquisition which is needed to perform EIS. The typical output of an EIS measurement on a fuel cell, is a Nyquist plot, which shows the imaginary and real part of the impedance of the measured system. The full stack impedance depends on the impedance of each of the single cells of the stack. Equivalent circuit models for each single cell can be used to predict the stack impedance at different temperature profiles of the stack. The information available in such models can be used to predict the fuel cell stack performance, e.g. in systems where different electronic components introduce current harmonics. Udgivelsesdato: 05/06/09 ; In designing and controlling fuel cell systems it is advantageous having models predicting fuel cell behavior in steady-state as well as in dynamic operation. This work examines the use of Electro-chemical Impedance Spectroscopy (EIS) for characterizing and developing an impedance model for a high temperature PEM (HTPEM) fuel cell stack. A Labview virtual instrument has been developed to perform the signal generation and data acquisition which is needed to perform EIS. The typical output of an EIS measurement on a fuel cell, is a Nyquist plot, which shows the imaginary and real part of the impedance of the measured system. The full stack impedance depends on the impedance of each of the single cells of the stack. Equivalent circuit models for each single cell can be used to predict the stack impedance at different temperature profiles of the stack. The information available in such models can be used to predict the fuel cell stack performance, e.g. in systems where different electronic components introduce current harmonics.