In contrast to the previous assumption that manganese (hydr)oxides, in the absence of other metal ions, exhibit high overpotentials for catalyzing the oxygen-evolution reaction (OER) under neutral conditions, this study uncovers a more nuanced behavior. We demonstrate that layered manganese oxides, when treated with carboxylate groups, exhibit OER activity at the Mn(III) to Mn(IV) oxidation peak following charge accumulation. Upon the addition of poly(acrylic acid) (PAA), the Mn(III) to Mn(IV) transition occurs at a lower potential. While the current density remains modest, this activity is observed at an extraordinarily low overpotential of just 20 mV in a phosphate buffer solution. We present a detailed mechanistic proposal for OER in this low-overpotential regime, focusing on the Mn(III) to Mn(IV) transition and the surrounding OER environment. Oxygen measurements reveal that at an applied potential of 1.25 V, the turnover frequency (TOF) increases from 2.6 × 10