The O₂ evolution reaction (OER) is an important anodic process for many aqueous electrochemical applications, including H₂ evolution from water and CO₂ reduction. Precious metals like Iridium, Ruthenium and/or Platinum are traditionally-used electrochemical anodes because they can efficiently oxidize H₂O into O₂ with high catalytic activity and good long term stability. However, recent efforts have tried to replace expensive precious-metal anodes with inexpensive and earth-abundant materials. Ni-based materials are promising replacements for precious metal-based OER catalysts because they show high activity and good long-stability. Unfortunately, the literature contains some debate as to the nature of the catalytic reaction center in Ni-based materials. This uncertainty stems from typical catalyst samples containing heterogeneous particle sizes and surface structures, and the literature contains a wide range of reported reaction rates and rate determining steps. My talk describes a combination of experimental and computational techniques to characterize the OER chemistry at an atomically-precise organometallic nickel complex. Single-crystal X-ray diffraction identified the catalyst’s crystal structure as a hexagonal “tiara-like” Ni₆(PET) structure (PET = phenylethyl thiol).  Laboratory and synchrotron-based X-ray spectroscopies were used to characterize the electronic structure of the Ni₆(PET)₁₂ complex (PET = phenylethylthiol). Electrocatalytic testing showed that Ni₆(PET)₁₂ outperformed bulk NiO and Pt, and that it had comparable OER performance to that of Ir. Density functional theory (DFT) was used to model the OER at a realistic Ni₆(SCH₃)₁₂ models to determined Gibbs free energy changes (ΔG) associated OER steps. Computationally predicted potential determining steps and OER onset potentials were in excellent agreement with experimentally-determined values. Interestingly, DFT results suggest subtle changes in adsorbate binding configuration can drastically alter the OER onset potentials. Our results highlight how atomically-precise nanocatalysts can facilitate the development of difficult-to-obtain structure-property relationships because they allow joint experimental and computational studies on nearly identical systems.