Two analogous coordination polymers with a composition of [Co(μ-dppeO2)X2]n (dppeO2 = 1,2-bis(diphenylphosphino)ethane dioxide; X = Br, I) were successfully prepared in crystalline form by a reaction of 1,2-bis(diphenylphosphino)ethane (dppe) and corresponding cobalt(II) halide in dichloromethane–ethanol mixture under aerobic conditions. The results of single-crystal X-ray structure analysis have shown that both complexes form one-dimensional chains in which the dppeO2 functions as a bidentate O,O′-donor ligand bridging the cobalt(II) central atoms. The Co(II) atoms are hence tetracoordinated by two oxygen atoms from two distinct molecules of dppeO2 and two halogenido ligands yielding a distorted tetrahedral chromophore of {CoO2X2} (X = Br, I). Spectral properties of both complexes were studied by IR and UV–Vis spectroscopy. Moreover, crystal structure of two unprecedented polymeric complexes [Co(μ-dppeO)Br2]n and {[Co(μ-dppeO)Br2][Co(μ-dppeO2)Br2]}n isolated from the system CoBr2-dppe has been revealed.