The catalytic activity of two iron-based porphyrin complexes containing pyridine-functionalized second coordination spheres, referred to as Py₂XPFe and CuPy₂XPFe, have been investigated for the hydrogen evolution reaction (HER) and compared with the unsubstituted analog TMPFe in acetonitrile. The CuPy₂XPFe incorporates a second metal center within the pyridine residues and represents a heterodinuclear system, while the structurally analogous Py₂XPFe lacks an additional metal in the second coordination sphere. Both the Py₂XFe and CuPy₂XPFe complexes are observed to activate the weak acid, acetic acid (AcOH) at the Fe^II/I couple rather than at the more energy intensive Fe^I/0 couple observed for the unfunctionalized TMPFe complex at low acid concentrations. The ability of the monometallic Py₂XPFe to activate the weak proton source at the Fe^II/I couple manifests as an ECEC(E)′ type electrochemical mechanism, rather than an EECC(E)′ type mechanism as observed for TMPFe. The CuPy₂XPFe displays improved reactivity compared with the Py₂XPFe and TMPFe under the same substrate conditions, however the mechanistic nuances into bimetallic CuPy₂XPFe system are currently unclear. The concentration of AcOH was incrementally increased and the rate constants of the initial protonation step i. e. formation of a hydridic species (k_1,app), as well as of the protonation of the hydridic species to produce dihydrogen (k_global) were calculated using the Foot-of-the-wave and plateau current rate equation methodologies, respectively. The kinetic analysis indicates that the activation of protons through the ECEC(E)′ type mechanism for the Py₂XPFe results in a system in which k_1,app< k_global. As both the monometallic Py₂XPFe and bimetallic CuPy₂XPFe activate the AcOH at less cathodic potentials than TMPFe under identical conditions, the overpotentials (η_TOF/2) for these complexes are thus dramatically lower. The reactivity difference of the Py₂XPFe when compared to non-substituted iron porphyrin analogs is due to the hanging group's influence, which is believed to either act as hydrogen bond promoters for the active site or aids to stabilize a catalytic intermediate species during catalysis.