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The enhancement of microbial electrosynthesis (MES) of acetate from CO₂ to performance levels that could potentially support practical implementations of the technology must go through the optimization of key design and operating conditions. We report that higher proton availability drastically increases the acetate production rate, with pH 5.2 found to be optimal, which will likely suppress methanogenic activity without inhibitor addition. Applied cathode potential as low as −1.1 V versus SHE still achieved 99% of electron recovery in the form of acetate at a current density of around −200 A m^–2. These current densities are leading to an exceptional acetate production rate of up to 1330 g m^–2 day^–1 at pH 6.7. Using highly open macroporous reticulated vitreous carbon electrodes with macropore sizes of about 0.6 mm in diameter was found to be optimal for achieving a good balance between total surface area …