Porphyrins have attracted interest as bioinspired molecular catalysts for decades, and have been extensively researched in this regard. However, reported reaction mechanisms, reduction potentials, protonation sites and electronic structures vary widely [1] and the exact nature of the electrochemical and catalytic properties of porphyrins remains elusive. Given the increasing prevalence of computational modeling in the field of molecular catalysis, these fundamental properties of prospective families of molecular catalysts must be well understood. The purpose of this work is a computational deep dive into catalysis of the hydrogen evolution reaction (HER) by tetraphenylporphyrins (TPP). I will investigate the effects of protonation site, applied potential, proton source and solvent on the catalytic mechanism. I will also construct a computational model for translating pKa values between different solvents, by calculating relative pKas of a large number of acids in several solvents and calibrating them against known experimental values in acetonitrile. Finally, I will optimize the suggested catalytic cycles in terms of proton source and applied potential; by artifically flattening the thermodynamic energy landscape of each reaction cycle I will produce suggested routes for catalyst optimization. [1 ]Lei, H.; Li, X.; Meng, J.; Zheng, H.; Zhang, W.; Cao, R. Structure Effects of Metal Corroles on Energy-Related Small Molecule Activation Reactions. ACS Catal. 2019, 9 (5), 4320–4344.