Heteroleptic complexes of terbium(III) phenylanthranilate with triphenylphosphine oxide of composition Tb(PA)3(TPPO)n (n = 1 or 2) were synthesized and characterized by elemental analysis, IR and photoluminescence spectroscopy, and thermal analysis. The structures of Tb(PA)3(TPPO)2 and Tb(PA)3(Phen) in solution were studied by the MALDI TOF-MS method. The photoluminescence properties of the terbium(III) complex with phenylanthranilic acid were compared with those of the terbium(III) complex with salicylic acid. An electroluminescent device with the structure ITO/PEDOT : PSS/PVC/Tb(PA)3(TPPO)2 /Al was constructed. The possibility of using heteroleptic aromatic carboxylates as emission layers for the construction of electroluminescent devices was exemplified by the Tb(PA)3(TPPO)2 complex