The defect structure for Mn2+ in KTaO3 is theoretically studied by using perturbation formulas of the spin Hamiltonian (SH) parameters for 3d(5) ions in tetragonal symmetry based on the strong-field scheme. By analyzing the electron paramagnetic resonance (EPR) data of the studied system, we suggest that the impurity Mn2+, ion occupy the dodecahedral K+ site, rather than the octahedral Ta5+ site. Based on the studies, it is found that the Mn2+, impurity undergoes an off-center displacement away from the ideal K+ site by about 0.60 angstrom along the C-4 axis. The above displacement is qualitatively consistent with the recent result based on the generalized gradient approximation (GGA) and that obtained from EPR and dielectric spectroscopy studies. (c) 2005 Elsevier Ltd. All rights reserved.