The development of non-precious metal-based oxygen evolution reaction (OER) electrocatalysts is one of the keys to lower the cost of various renewable energy technologies including fuel cells, water electrolyzers, and metal-air batteries. Perovskite oxides are among the best catalysts for OER in alkaline solutions. In the perovskite family, La0.8Sr0.2CoO3-δ (LSC) has been reported to have OER catalytic properties dependent on the characteristics of its surface, but where its activity and stability are still not high enough for applications. In order to improve the surface catalysis of LSC, we have subjected it to multiple H2O2 treatments. After 4 treatments, lasting 6hours each, the current density of LSC at 1.70V (vs RHE) increased by a factor of 6.6 and concomitantly, the Tafel slope decreased from 105.5 to 76.6 mVdec−1 compared to untreated materials. The long-term stability also improved dramatically after treatment. All these improvements are likely linked to the formation of an amorphous layer of hydrous oxide on the LSC particles during treatment.