The V atoms are in the octahedral coordination. <...> Thermal stability of the complexes is also studied. <...> In recent years, vanadium complexes have been reported to have interesting biological activities such as normalizing the high blood glucose levels and acting as models of haloperoxidases [ 5—9]. <...> It is notable that Ara and co-workers reported that some binuclear vanadium(IV) complexes possess interesting urease inhibitory activities [ 10 ]. <...> Aslam and co-workers reported that the Schiff bases of hydrazone type also possess urease inhibitory activities [ 11 ]. <...> Recently, our research group has reported a few vanadium complexes with biological activities [ 12, 13 ]. 8-Hydroxyquinoline (HQ) is a widely known bidentate ligand in coordination chemistry [14—16 ], however, only two HQ coordinated oxovanadium complexes with hydrazone ligands have been reported so far [ 17, 18 ]. <...> In the present paper, two new oxovanadium(V) complexes with hydrazone and HQ ligands, [VOL1(HQ)] (1) and [VOL2(HQ)] (2) (H2L1 = 4-bromo-N-(3-ethoxy-2-hydroxybenzylidene)benzohydrazide, H2L2 = 2-bromo-N-(3-ethoxy-2-hydroxybenzylidene)benzohydrazide; Scheme 1), have been presented. © Sheng G.-H., Cheng X.-S., You Z.-L., Zhu H.-L., 2015 ethoxy-2-hydroxybenzylidene)benzohydrazide (H2L2), respectively, in methanol. <...> Crystal and molecular structures of the complexes are determined by elemental analysis, infrared spectroscopy, and single crystal X-ray diffraction. <...> C, H, and N elemental analyses were performed with a Perkin-Elmer elemental analyzer. <...> Infrared spectra were measured on a Nicolet AVATAR 360 spectrometer as KBr pellets in the range 4000—400 cm–1. <...> Thermal stability analysis was performed on a Perkin-Elmer Pyris Diamond TGA-DTA thermal analysis system. <...> A methanolic solution (10 ml) of [VO(acac)2] described for 1, with H2L1 replaced by H2L2. <...> Brown block-shaped crystals suitable for X-ray single crystal diffraction formed at the bottom of the vessel. <...> The collected data were reduced using the SAINT program [ 21 ], and multi-scan absorption corrections were performed using the SADABS program [ 22 ]. <...> The replacement of two acetylacetonate ligands of [VO(acac)2] by hydrazone and hydroxamate ligands in methanol resulted in the formation of two structurally <...>