The coordination chemistry of vanadium involving N-O donor ligands has attracted much interest of inorganic and bioinorganic chemists in recent years. Owing to the presence of different kinds of potential donor sites, we selected carbohydrazones as building blocks in the self-assembly of polynuclear compounds. Tetranuclear complexes (1–3) were synthesized from the reaction of [VIV O(acac) 2] with H 4L1–3 in 1:2 molar ratio (H 4L is the general abbreviation of Schiff base ligands derived from the condensation of carbohydrazide with either salicyl aldehyde (H 4L1 ) or its 3-methoxy- (H 4L2 ) or 3,5-di-tert-butyl (H4L3 ) substituted derivatives) in methanol or ethanol. During this reaction, vanadium(IV) is oxidized by oxygen of air and vanadium(V) compounds with the compositions [(VO 2)(VO)(CH 3O)(HL 1 )]2·3CH 3OH (1), [(VO 2)(VO)(C2H 5O)(HL 2 )]2·2C2H 5OH (2), [(VO 2)(VO)(C2H 5O)(HL 3 )]2·3C2H 5OH (3) were isolated. The new clusters were characterized by IR and NMR spectroscopy, X-Ray diffraction, EPR and electrochemical measurements. There are two common structural features in the two oxovanadium complexes. They represent cyclic tetranuclear oxovanadium complexes where two {OVV (μ-O)VV O}4+ cores are bridged by diazine fragment –N–N– of Schiff base ligands. The coordination geometry at the two different vanadium atoms varies: a distorted octahedral geometry is found for the sixfold coordinated VV -ion whereas a square-pyramidal/trigonalbipyramidal one is found for the fivefold coordinated VV -ion. This work was supported by the DAAD (postdoctoral fellowship for D.D.) and Swiss National Science Foundation (SCOPES IZ73Z0_127925).