Abstract The luminescence properties of the Gd3+ ion in LiYF4 and the energy migration among the Gd3 ions via the 6P7/2 level and the 6I7/2 level in the isostructural compound LiGdF4 are reported. The isolated Gd3+ ions in this structure show efficient emission from the 6I level. The non-radiative 6I → 6P relaxation can be ascribed by a 5-phonon relaxation process, involving 490 cm-1 phonons which are available from the Au vibrational mode. The decay of the Gd3+ emission in Li(Y, Gd)F4-Tb3+ can be described by a theory of energy migration developed by Burshtein et al. Parameters following from these fits indicate that the energy migration among the Gd3+ ions via the 6P7/2 level and via the 6I7/2 level is governed by exchange interaction. Parameters for the Gd3+ -Gd3+ and Gd3+ -Tb3+ transfer rates in this structure are given.