The luminescence properties of Cs2 NaGdCl6 are reported. In the emission, as well as the excitation spectra of the Gd3+ luminescence, vibronic lines are present due to coupling with the ν3 , ν4, and ν6 vibrational modes of the GdCl3−6 octahedron. The magnetic–dipole character of the zero-phonon transitions is confirmed by the long decay time of the 6 P7/2 emission. Energy migration among the Gd3+ ions is absent, due to the large distance (7.6 Å) between nearest-neighbor Gd3+ ions. The emission from two extrinsic Gd3+ ions shows a coupling with the O–H stretching and bending modes.