Abstract Electrochemical oxidation of propylene offers a low‐temperature, electricity‐driven route to produce valuable oxygenates using water as the sole oxygen source. Selectivity, however, remains difficult to control because multiple oxygen species including *OH, *O, *OOH, and lattice oxygen can form simultaneously under applied potential. How these species originate, interconvert, and engage in C–O coupling is central to designing selective catalysts. Recent advances in operando x‐ray and vibrational spectroscopy, electrochemical mass spectrometry, and complementary theoretical tools such as Pourbaix analysis and microkinetic modeling now enable potential‐dependent surface oxidation and oxygenated intermediates to be resolved with much greater clarity. Collectively, these developments reveal that propylene electrooxidation does not follow a single universal mechanism but spans distinct oxygen‐speciation regimes. This review shows mechanistic insights across Pd‐ and Pt‐based catalysts, Ag‐based systems, and transition metal oxides, illustrating how each class stabilizes different reactive oxygen species and thus accesses different C–O coupling pathways. We conclude by highlighting remaining challenges that define the path toward rational, design‐based catalyst development.
Rasool et al. (2026) studied this question.