AbstractA nearly stoichiometric SrCoO3phase had been prepared up to now only using high oxygen pressure. A new method for preparing fully stoichiometric SrCoO3has been proposed using electrochemical oxidation. Brownmillerite‐type SrCoO2.50is oxidized into a completely stoichiometric perovskite at a potential of 500 mV for 180 hours at room temperature in alkaline media (1 M KOH). The oxidized phase has a cubic unit cell (a=383.5 pm). It is metallic and, at temperatures below T=280 K, it shows ferromagnetic behavior. The magnetic moment at 0 K is 2.1 μB. The physical properties of SrCoO3.00have been explained in terms of partial occupancy of a σ*e g