Fuel Cells (FCs) constitute an enabling technology for the integration of renewable energies and for the deployment of the next generation of power grids, the so-called Smart Grids/Microgrids. These devices perform the process of converting hydrogen into electricity without pollutant emissions. Characteristic curves, mainly polarization curves, are a paramount resource to study the performance of FCs and to determine accurate models that fit their behaviour. This paper presents the characterization of a commercial Polymer Electrolyte Membrane (PEM) FC consisting of 24 cells in series, with a nominal output of 500 W, used to supply electricity in a Smart Microgrid involving renewable energies and hydrogen. The process evolution takes place under different laboratory conditions, so voltage, current and hydrogen flow are measured and plotted to build the polarization curves. The equipment and components involved in the operation of the FC are described, as well as their technical features. Namely, a metal-hydride bottle is used to store the hydrogen that feeds the FC, an electronic programmable load establishes different charge conditions, and a precision multimeter collects the measurements provided by a set of sensors physically coupled to the FC. The characterization conducted in this research is envisioned to be used to build a digital twin of the FC. The developed experimentation and achieved results are described. The obtained results show a proper matching between the experimental data and the curves reported in literature and in the FC datasheet.