Spectrophotometric analysis of the complexation of 8-hydroxyquinoline (8-HQ) with cerium(IV) has been performed. The Ce-8-HQ complex was prepared and characterized using FT-IR and UV-VIS absorption spectral data. According to the spectral data, both oxygen and nitrogen atoms from 8-HQ were involved in the complex formation. The stoichiometry and formation constant (Kf) of 8-HQ ligand with cerium(IV) ion were determined using the mole-ratio method at constant temperature, with the molar ratio and Kf of this complex being 1:2 (metal:ligand) and 1.308 x 1014, respectively. Beer's law was followed with a molar absorptivity (ε) of 22089 l-1.mol-1.cm-1 at λmax = 253 nm in the range 2.0 x 10-5-5.0 x 10-5 M. In vitro antimicrobial effects of the ligand and complex were also investigated. The biological study data confirmed that each of the investigated compounds, i.e. ligand and complex, has the best pastime against all of the microorganisms studied. However, comparing the spots between concentrations of cerium (IV) complex with 8-hydroxy quinoline indicates a more potent pastime with maximum Gram-terrible.