<p>Performing electrolytic water splitting in acid can enable a step change in electrolyser technology, providing lower overpotential reactions and opportunities for membrane-free electrolysers. Decoupled acid electrolysis exploits H⁺ intercalation and pseudocapacitive reactions in transition metal oxides to temporally split the hydrogen and oxygen evolution reactions. While the performance of the transition metal oxide is critical to the overall efficiency of the decoupled electrolysis reactions, the role of the carbon support has not been explored. This is surprising as proton battery literature has shown the capacity of these supports to store H⁺ ions via similar intercalation reactions. Here, bio-derived activated carbons (AC) from Alder charcoal and Birch wood are prepared and compared with commercial conductive carbon additives for decoupled electrolysis in 0.5&#xa0;M H₂SO₄. The use of bio-derived activated carbons increases the pseudocapacitive performance by more than 280% (from 348.3 to 982.3 F/g) due to improved particle distribution. In decoupled electrolysis, the bio-derived AC/transition metal oxide electrode showed a remarkable faradaic efficiency above 92%, stable over 2000 cycles. This work has broad applicability to designing improved decoupled electrolysis electrodes, highlighting the role of the conductive carbon in achieving optimal reaction efficiencies.</p> Graphical abstract <p></p>