The magnetic environments of Cu2+ doped Na+ complex have been identified by electron paramagnetic resonance (EPR) technique. The angular variation of the EPR spectra has shown that two different Cu2+ complexes are located in different chemical environments, and each environment contains one magnetic Cu2+ site occupying substantial positions in the lattice and showing very high angular dependence. The principal g, and the hyperfine structure parameter (A) values of two sets of Cu2+ complex groups are determined. The covalency parameter, mixing coefficients and Fermi-contact term of the complex are obtained, and the ground state wave function of the Cu2+ ion in the lattice has been constructed. (C) 2009 Elsevier B.V. All rights reserved.