The development of highly efficient, robust, and cheap water oxidation electrodes is a major challenge in constructing industrially applicable electrolyzers for large-scale production of hydrogen from water. Herein we report a hierarchical stainless steel mesh electrode which features Ni(Fe)OxHy-coated self-supported nanocone arrays. Through a facile, mild, low-cost and readily scalable two-step fabrication procedure, the electrochemically active area of the optimized electrode is enlarged by a factor of 3.1 and the specific activity is enhanced by a factor of 250 at 265 mV overpotential compared with that of a corresponding pristine stainless steel mesh electrode. Moreover, the charge-transfer resistance is reduced from 4.47 Omega for the stainless steel mesh electrode to 0.13 Omega for the Ni(Fe)OxHy-coated nanocone array stainless steel mesh electrode. As a result, the cheap and easily fabricated electrode displays 280 and 303 mV low overpotentials to achieve high current densities of 500 and 1000 mA cm(geo)(-2), respectively, for oxygen evolution reaction in 1 M KOH. More importantly, the electrode exhibits a good stability over 340 h of chronopotentiometric test at 50 mA cm(geo)(-2) and only a slight attenuation (4.2%, similar to 15 mV) in catalytic activity over 82 h electrolysis at a constant current density of 500 mA cm(geo)(-2).