The production of hydrogen from ecofriendly renewable technologies like water electrolysis and fuel cells involves oxygen evolution reaction (OER), which plays a major role, but the slow kinetics of OER is a bottleneck of commercialization of such technologies. Herein, we have reported the formation of an efficient OER catalyst from SnCo(OH)(6) (SCH) by leaching of Sn atoms during electrochemical OER studies. According to density functional theory calculations, adsorption of OH* species on Sn atoms is energetically more favorable than that of Co atoms, and as a result, highly active CoOOH is generated by leaching of Sn atoms from surface layers. We observed enhanced OER performance with superior mass activity by blending SCH with activated charcoal, which displays a low overpotential of 293 mV and higher mass activity than that of pristine SCH. More importantly, it outperforms Co(OH)(2) and RuO2 having the same carbon composition because of the formation of thermodynamically stable and amorphous CoOOH on the surface of single-crystalline SCH and strong tethering ability of activated charcoal.