A series of new complexes of poly(styrene-co-methacrylic acid) with Ln(III) (Ln = La, Eu, Tb) were synthesized and well characterized by means of elemental analysis, FTIR, differential scanning calorimetric (DSC) analysis, TG-DTA analysis, X-ray diffraction (XRD), and fluorescence determination. The elemental analysis and FTIR studies showed that a large part of carboxylic groups on the side chain of the copolymer are coordinated with Ln(III) ions. The TG-DTA and DSC analysis results indicated that the complexes have good thermal stability. XRD experiments showed that copolymers and the complexes are amorphous. Among these complexes, Eu(III) complexes and Tb(III) complexes exhibit characteristic fluorescence with comparatively high brightness and good monochromaticity. (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 112: 3388-3394, 2009