Efficient and durable electrocatalysts for the oxygen evolution reaction (OER) play an important role in the use of hydrogen energy. Rutile RuO 2 , despite being considered as an advanced electrocatalyst for the OER, performs poorly in stability due to its easy oxidative dissolution at very positive (oxidizing) potentials. Herein, we report a type of Co-doped RuO 2 nanoparticle for boosting OER catalytic activity and stability in alkaline solutions. The replacement of Ru by Co atoms with a lower ionic valence and smaller electronegativity can promote the generation of O vacancies and increase the electron density around Ru, thus enhancing the adsorption of oxygen species and inhibiting the peroxidative dissolution of RuO 2 during the OER process. It was found that Ru 0.95 Co 0.05 O y exhibited excellent OER performance with overpotentials as low as 217 mV at 10 mA cm -2 and 290 mV at 100 mA cm -2 in 1 M KOH, as well as outstanding stability in continuous testing for 50 h at a current density of 100 mA cm -2 , and nearly no significant degradation after the accelerated durability test of 2000 cycles.