Various metalloenzymes employ O2 for oxidative reactions, which is crucial in catalysis and biological processes involving high-valent metal-oxygen species. This study introduces novel high-valent Co(III)-(μ-1,2-O2)-Co(IV) and Co(III)-(μ-1,2-O2˙-)-Co(III) complexes, stabilized by an electron-donating TPA* ligand. This study advances our understanding of Co-oxygen intermediates, which are key for water oxidation catalysis.