Poly acrylic acid (PAA) and its stoichiometric complexes with trivalent rare earth (RE) have been synthesized and well characterized by means of elemental analysis, IR, TG-DTA, fluorescence spectra, etc. Chemical analysis indicated that the molar ratio of -COO- and RE(3+)in the complex was closely dependent on the pH and the molar ratio of PAA and RE in the feed. The stoichiometric complexes in which the molar ratio of -COO- and RE3+ is 3:1 can be formed under the conditions of pH 6.0 and PAA:RE = 3:1 (molar ratio in the feed). Spectroscopic studies suggested that the carboxylate bonded to the central metal ions was in the form of bidentate and these stoichiometric complexes possessed high-temperature resistance. Due to efficient energy transfer from polymer to central metal ions, the emission intensity of Eu3+ and Tb3+ complexes was stronger than that of simple compounds. Therefore, these complexes can be promising as potential fluorescent probes and photoluminous materials. (C) 2006 Wiley Periodicals, Inc. J Appl Polyrn Sci 103: 351-357, 2007