Luminescence spectra of [Eu(NTA) 2 .H 2 O] 3 - and [Tb(NTA) 2 .H 2 O] 3 - crystals measured at 78.8 K are reported. When the crystals are excited by UV light, they produce very characteristic luminescence lines in the 580-720 nm region for [Eu(NTA) 2 .H 2 O] 3 - and in the 450-700 nm region for [Tb(NTA) 2 .H 2 O] 3 - . The energy-level schemes of the 7 F J states and the emitting level for Eu(III) and Tb(III) ions have been proposed by phenomenological simulation in the framework of crystal-field Hamiltonian. The set of refined crystal-field parameters under the C 2 V site symmetry of the two ions satisfactorily produce good fits between calculated and experimentally observed energy-level structures, associated with the fine splitting of the luminescence lines in the 5 D 0 -> 7 F J (J=0-4) transitions of the Eu(III) ion in [Eu(NTA) 2 .H 2 O] 3 - and in the 5 D 4 -> 7 F J (J=6-0) transitions of the Tb(III) ion in [Tb(NTA) 2 .H 2 O] 3 - .