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Uninuclear europium (Eu), as well as binuclear Eu and terbium (Tb), complexes were synthesized using acrylic acid (AA) as the first ligand and 1,10-phenanthroline (Phen) as the second ligand. The relative weight ratio of the europium (III) (Eu3+) to terbium (III) (Tb3+) ions of the binuclear complex was 1:1 as determined via energy dispersive X-ray analysis. The structures of the Eu(AA)3Phen and Eu0.5Tb0.5(AA)3Phen complexes were characterized by Fourier transform infrared spectroscopy. A series of tri-cellulose acetate (TCA)/ the Eu(AA)3Phen and TCA/Eu0.5Tb0.5(AA)3Phen composites were prepared by solution blending, and their luminescent properties were investigated by fluorescence spectrophotometry. The excitation spectra of all composites indicated that the TCA matrix probably affected the energy absorption and transfer of organic ligands. In TCA/Eu0.5Tb0.5(AA)3Phen composites the introduced Tb3+ions had some influence on energy absorption and transfer of organic ligands; the energy transfer process of the complex is suggested to be as follows: Phen→AA→Tb3+ion→Eu3+ion. The emission spectra indicated that the luminescent intensity of the TCA/Eu0.5Tb0.5(AA)3Phen composites was noticeably stronger than that of the TCA/Eu(AA)3Phen composites, suggesting that the comparatively stable and high-efficiency energy transfer process was only slightly influenced by the TCA matrix. In summary, the TCA/Eu0.5Tb0.5(AA)3Phen (90/10) composite possesses fine luminescent properties for potential usage as red fluorescent materials. [ABSTRACT FROM AUTHOR]