We report the reaction mechanism of the oxygen evolution reaction catalyzed by penta-coordinated [(CoV(TPA-αF3)(O))]3+(TPA = tris-(2-pyridylmethyl)amine) and hexa-coordinated [CoV(TPA-αF3)(O)OH]2+cobalt complexes for the formation of the oxygen-oxygen bond and the role of fluorination with the help of density functional theory. The nature of the orbitals involved in the formation of the oxygen-oxygen bond by these complexes is examined. The formation of the oxygen-oxygen bond occurs by the interaction of the dx2−y2* orbital of metal with the σ*-orbital of the hydroxide in the case of [(CoV(TPA-αF3)(O)OH]2+, while, in the case of [(CoV(TPA-αF3)(O))]3+, the dz2*-orbital accepted the electron from the hydroxide. The activation barrier for the oxygen-oxygen bond formation by the penta coordinated complex is lower than that of the hexa-coordinated complex. The release of oxygen through both the catalytic processes has nearly equal activation free energies. From the spin density analysis, we observe that the oxo-complexes are stabilized by sharing the spin density on the nitrogen atoms with fluorine atoms of the modified TPA ligand. Comparing the four-proton and four-electron process of the catalytic cycle with both catalytic species, it is found that the penta-coordinated complex ([(CoV(TPA-αF3)(O))]3+) requires a lower activation free energy barrier than the hexa-coordinated complex [CoV(TPA-αF3)(O)OH]2 © The Royal Society of Chemistry 2021.