The synthesis and structure determination of five novel lanthanide complexes {[Ln(3,5-DmeoxBA)(3)(-phen)](2) (Ln = Pr(1) Nd (2), Sm (3), Eu (4), and Ho (5); 3,5-DmeoxBA = 3,5-Dimethoxybenzoate; phen = 1,10-phenanthroline)} are reported. In the isomorphous complexes 1 to 5, two Ln(3+) ions are connected together by four bridging 3,5-DmeoxBA ligands. Each Ln(3+) ion is octa-coordinated, yielding a distorted square-antiprism comformation. The thermal properties of the title complexes were investigated by simultaneous TG/DSC-FTIR techniques. The activation energy E values of the first decomposition stage for complexes 1 to 5 were calculated by integral iso-conversional non-linear (NL-INT) and Starink methods. Heat capacities of the five complexes were measured by differential scanning calorimetry (DSC). And the values of the experimental heat capacities were fitted to a polynomial equation with the least-squares method. Furthermore, based on the fitted polynomial and thermodynamic equations, the smoothed heat capacities and thermodynamic functions (H-T-H-298.15K), (S-T-S-298.15K), and (G(T)-G(298.15K)) were calculated. The fluorescent property of complex 4 was also studied. (C) 2012 Elsevier Ltd. All rights reserved.