Herein, a mixed-phase nickel boride/cobalt oxide/cobalt hydroxide, Ni x B/Co 3 O 4 /Co(OH) 2 , composite was formed to give a scalable and non-precious pre-catalyst for the oxygen evolution reaction (OER) in alkaline medium. The material was synthesised via a simple chemical reduction method, where amorphous Ni x B particles were deposited onto cobalt oxide rods undergoing partial transformation into Co(OH) 2 sheets. This approach suppresses the agglomeration of Ni x B particles, increasing surface accessibility. The optimised composite (Ni x B/Co 3 O 4 -100 mg/Co(OH) 2 ) achieved a low overpotential of 370 mV at 100 mA cm −2 . It retained 99.2% of its activity after more than 90-h of continuous operation at 100 mA cm −2 for the OER in 1.0 M KOH, indicating excellent stability. Electrochemical impedance analysis revealed a 20-fold increase in the electroactive surface area compared to the bare substrate. XPS analysis following stability testing under OER conditions confirmed a full surface reconstruction, with the loss of boron from the surface and formation of catalytically active NiOOH and CoOOH species, indicating that Ni x B, Co 3 O 4 and Co(OH) 2 act as precursors to the true active phase. This work highlights a practical strategy for designing robust, non-precious OER catalysts through the phase reconstruction of boride/oxide hybrids.