EPR spectroscopic investigations on single crystals of diaquabis[malonato(1-)-κ 2 O,O′] zinc(II) doped with VO(II) ion have been carried out at X-band frequencies and at 300K. The single crystal, rotated along the three mutually orthogonally axes, has yielded spin-Hamiltonian parameters g and A as: g xx =1.980, g yy =1.972, g zz =1.937 and A xx =8.4, A yy =6.1, A zz =18.1mT, respectively. These spin-Hamiltonian parameters reflect a slight deviation from axial symmetry to rhombic, which is elucidated by the interstitial occupation of vanadyl ions. The isofrequency plots and powder EPR spectrum have been simulated. The percentage of metal-oxygen bond has been estimated. The optical absorption spectrum exhibits four bands at 257, 592, 720 and 764nm suggesting a C 4v symmetry. The admixture coefficients and bonding parameters have also been calculated by collaborating EPR data with optical data.