In this study, synthesis and characterization of oligomer [Co21(phen)42(bipy)42]Cl42 and polymer [Co100(phen)200(bipy)200]Cl200 complexes of Cobalt(II) (phen=1,10-Phenanthroline, bipy=4-4'- Bipyridine) was done. The complexes were synthesized by a high dilution method by refluxing a starting complex having a formula of [Co(phen)2(H2O)2)]Cl2 with 4-4'-bipyridine. The physicochemical characterizations (halide test, melting point, conductivity, and solubility) and spectroscopic characterization of these compounds have been studied by flame atomic absorption spectroscopy (FAAS), Fourier transform infrared spectrometry (FTIR), UV-visible spectroscopy as well as cyclic voltammetry. The evidences obtained from all these techniques supported the synthesis of the complexes. The synthesized complexes were used for the modification of glassy carbon electrode (GCE) surfaces to test for sensor applications. [Co21(phen)42(bipy)42]Cl42 was found to be able to polymerize on the electrode surface. The electrochemical impedance data of [Co21(phen)42(bipy)42]Cl42/GCS showed lower charge transfer resistance and enhanced effective electrode surface area of the glassy carbon electrode. [Co21(phen)42(bipy)42]Cl42/GCS was tested as sensor for determination of Ciprofloxacin (Cipro) in four brands of tablet formulation sample under optimized solution and the selected parameters. The oxidative current response of [Co21(phen)42(bipy)42]Cl42/GCE showed linear dependence on concentration of Cipro in the range between 0.1-200 μM. The detected content of Cipro in four tablet brands were in the range 95.00–99.75% of their labeled values which confirmed potential applicability of the developed new coordination polymer sensor with a good precision and accuracy. Therefore, poly[Co21(phen)42(bipy)42]Cl42/GCE may be fabricated for determination of Cipro in real sample with complex matrix