High entropy oxides (HEOs) are a novel class of materials with a stable single‐phase structure that is often entropy stabilized and possess many interesting functional properties. In this work, we report a nanocrystalline spinel‐based high entropy oxide (SP‐HEO) ‐ (Al0.2Co0.2Cr0.2Mn0.2Ni0.2)3O4 and present an assessment of its electrochemical performance. A reverse co‐precipitation (RCP) method was used for synthesis, followed by a suitable heat‐treatment/calcination step that was adjusted to form a single‐phase nanocrystalline powder. Structural characterisation revealed that the single‐phase system was stable upto 850 °C. Nitrogen adsorption studies showed a large specific surface area of 90 m2 g−1 in the case of the SP‐HEO calcined at 550 °C. The SP‐HEO powders were investigated as electrodes for battery‐like supercapacitor behaviour in an aqueous alkaline electrolyte ‐ KOH. The SP‐HEO powder calcined at 550 °C exhibited the highest specific capacity of 318 mAh g−1 at a current density of 1 A g−1. The high electrochemical performance of the mesoporous SP‐HEO makes it a promising electrode material for energy storage devices. [ABSTRACT FROM AUTHOR]