Fluorescence spectra and lifetimes originated from both D-5(3) -> F-7(J) and D-5(4) -> F-7(J) transitions of Tb3+ were measured using time-resolved laser fluorescence spectroscopy in order to investigate the excited state relaxation in a molten salt medium. A cross-relaxation energy transfer of D-5(3) -> D-5(4) resulted in rise and decay behaviors in fluorescence signal waveforms of D-5(4) -> F-7(J) transitions. The fluorescence intensity ratios of D-5(4) -> F-7(5) to D-5(3) -> F-7(4) decreased drastically when the temperature of molten salt increased. This result suggests that the cross-relaxation effect becomes weakened with increasing temperature. In addition, a strong increase of the D-5(4) emission over the D-5(3) emission was observed at high Tb3+ concentration. (C) 2010 Elsevier B. V. All rights reserved.