Chlorins have presented an interesting new class of catalysts for activation of small molecules of energy consequence, more specific, chlorins exhibited higher catalytic activity in hydrogen evolution at low overpotentials versus its porphyrin congeners. A hangman chlorin with a xanthene backbone and a carboxylic acid hanging group positioned above the redox-active macrocycle catalyzes the electrochemical production of hydrogen from trifluoroacetic acid (TFA) and benzoic acid in acetonitrile solutions. The hangman motif provides mechanistic insights into the role of pendant proton relays in governing proton-coupled electron transfer (PCET) involved in the HER. HER by Co chlorins in strong and weak acid reveals Co(II)H is exclusively involved in the generation of H₂, but a hydrogen evolution mechanism proceeds by an ECEC mechanism in TFA solution or an EECC mechanism in benzoic acid solution, respectively. Overpotentials for H₂ generation are lowered as a result of the hangman effect.