The synthesis and spectroscopic and EPR characterization of a vanadyl complex with acetone Schiff base, bis(S-methyl-3-isopropylidenehydrazinecarbodithioato)oxovanadium(IV), are described. The magnetic moment of 1.75 mu(B) at room temperature is close to the spin only magnetic moment (1.73 mu(B)). The experimental values of g(parallel-to) = 1.960 and g(perpendicular-to) = 1.988 and the normal occurence of nu(V=O) vibration suggest a monomeric five-coordinate square pyramical structure of the complex. A correlation was found between g(parallel-to) and A(parallel-to) of the title compound when compared with other model compounds of the vanadyl complexes in which possible combinations of four ligands may include all nitrogen (N4) and all sulfur (S4). This information could be useful in characterizing aqueous pyridine cuts of asphaltenes with molecular weights less than 400 found in some heavy crude oils.