A pair of structurally similar oxidovanadium(V) complexes with the general formula [VOLL'], with the hydrazone compounds N'-(4-oxopentan-2-ylidene)nicotinohydrazide (H2L1) and 4-bromo-N'-(4-oxopentan-2-ylidene)benzohydrazide (H2L2), and the acetohydroxamic acid (HL') as ligands, have been synthesized and structurally characterized by physico-chemical methods and single crystal X-ray determination. Single crystal X-ray analysis indicates that the V atoms in the complexes are in octahedral coordination, with the ONO donor atoms of the hydrazone ligands, and the OO donor atoms of the acetohydroxamate ligands, as well as an oxido O atom. The complexes showed good property for the catalytic epoxidation of styrene.