A novel diagnostic tool and methods to characterize the catalyst component durability for sixteen-segmented membrane electrode assembly is developed. The heterogeneity in the cell is proved from the effective platinum surface area (EPSA) computed from the cyclic voltammogram. The kinetic loss, polarization resistance and EPSA loss of the end of life outlet segment increased to 4%, 14%, and 21%, respectively from that of the inlet. Pt dissolution rate increased by 50% at the outlet compared to the inlet segment reducing the durability of the cell. The EPSA-kinetic loss relationships suggested higher degradation in a segmented cell compared to those of a non-segmented cell. During the AST, the variations in the local operating parameters of each segment (e.g., relative humidity, temperature and pressure) are used to explain the differences in Pt dissolution rates and kinetic losses across the segmented cell. © 2014 The Electrochemical Society.