[Fe-Fe]-hydrogenases are a class of metalloenzymes that catalyze the production of H-2 from two protons and two electrons. In this work, we used density functional theory (DFT) calculations to analyze the mechanism of hydrogen production, providing insight into the role of the intermediates in the catalysis. We also validated the exchange-correlation functional applied within DFT for model compounds of the active site in [Fe-Fe]-hydrogenase, enabling us a reliable application for understanding previously established hydrogen production hypotheses, as well as providing a starting point for a future investigation of the effects of the protein environment on the catalytic mechanism of [Fe-Fe]-hydrogenases.