Water electrolysis Stainless steel is widely used in water electrolysis industry due to its high corrosion resistance. But due to the lack of active species on the surface, the activity of stainless steel is still far from satisfactory. In this work, we developed a universal and one-step activation strategy to quickly convert the surface of stainless steel into hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) active species. Specifically, high temperature annealing (~1000 °C) was first applied to heat the stainless steel in air. Subsequently, the heated stainless steel was quickly quenched in Ni(NO3)2 aqueous solution to activate its surface into HER and OER active species. The activated stainless steel was denoted as Ni-SSM. After the activation, the Ni-SSM delivered 500 mA/cm2 HER current density at the overpotential of 271 mV and OER at the overpotential of 310 mV in 1 M KOH. Due to the efficient performance of HER and OER, Ni-SSM exhibited excellent overall water electrolysis performance in 1 M KOH, delivering 500 mA/cm2 at 1.846 V and 1.650 V at 25 and 60 °C, respectively. The Ni-SSM were further tested in the industrial used 6 M KOH to investigate the activity and stability under industrial condition. The Ni-SSM delivered 500 mA/cm2 at 1.779 and 1.615 V at 25 and 60 °C in 6 M KOH, respectively. At 500 mA/