The theoretical study on magneto-structural correlation in axially coordinated copper(II)-nitronyl nitroxide complex has been performed using the broken symmetry approach with the framework of density functional theory. The exchange interaction between Cu(II) ion and nitronyl nitroxide radical is propagated through a mechanism involving interaction between orthogonal orbitals. The spin density population shows that the electron transfer takes place from the Cu(II) ion to nitronyl nitroxide radical. The magnetostructural correlations indicate that both the variations of Cu-O distance and the Cu-O-N angle have significant influence on the magnetic exchange interaction. (c) 2005 Elsevier B.V. All rights reserved.