A least-square fitting method is given for exact evaluation of spin-Hamiltonian and line shape parameters from EPR powder spectra. The method is applicable to cases where the resonance fields can be analytically expressed or can only be obtained by diagonalization of Hamiltonian. It is also suitable for different line shapes and spin-Hamiltonians. The fitted spectra and corresponding refined parameters were obtained on FACOM-M340S computer with a Fortran 77 program. Keywords: spin-Hamiltonian, line shape parameters, electron paramagnetic resonance, calculated spectra, least squares fitting
