Four cobalt corrole complexes bearing 0–3 cyano groups on the para-position of the three meso-phenyl rings of the macrocycle were synthesized, characterized and applied for electrocatalytic H2 production in both organic solvent and neutral aqueous media.

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Three isomeric A2B‐type new cobalt triaryl corroles bearing hydroxyphenyl substituents have been prepared and well characterized. Their activity and stability in the electrocatalytic hydrogen evolution reaction (HER) have been investigated. The results showed that the hydroxyl position of the phenyl group had significant influence on electrocatalytic HER. The ortho‐hydroxyphenyl substituted cobalt corrole (1) core displays the best HER activity using TsOH proton source, and the turnover frequency (TOF) and catalytic efficiency (C.E) reach 318.68 s−1 and 1.13, respectively. Moreover, a turnover number (TON) of 1447.39 and Faraday efficiency (FE) of 98.7 % have been observed in aqueous medium. The catalytic pathway is via EECEC, EECC or ECEC pathways depending on the acidity of acid proton source (E: electron transfer step, C: chemical step, in this case protonation). The catalytic HER performance of these cobalt corroles follows an order of o‐hydroxyl > p‐hydroxyl > m‐hydroxyl isomer, showing the o‐ and p‐hydroxyl of the phenyl groups are more efficient in accelerating proton relay.