A binuclear holmium(III) benzoate 1,10-phenanthroline ternary complex, [Ho(BA)(3)phen](2), was synthesized and characterized by elemental analysis, IR and UV spectroscopy, molar conductance, single crystal X-ray diffraction, and thermogravimetric/differential thermogravimetric (TG-DTG) techniques. The crystal of the complex is in a triclinic crystal system, space group p (1) over bar with a = 10.7162(18) angstrom, b = 11.845(3) angstrom, c = 12.227(2) angstrom, alpha = 105.141(11)degrees, beta = 93.845(8)degrees, gamma = 112.880(5)degrees, and Z = 1. Each Ho(III) cation in the crystal is eight-coordinated including two O atoms of one chelating bidentate carboxylate group, four O atoms of four bridging bidentate carboxylate groups, and two N atoms of one 1,10-phenanthroline molecule, yielding a distorted square antiprismatic comformation. The thermal analysis of [Ho(BA)(3)phen](2) has been performed by simultaneous TG/DSC-FTIR techniques. By the Malek method, SB(m,n) was defined as a kinetic model for the second-step thermal decomposition. The activation energy E of this step is 296.99 kJ.mol(-1), and the pre-exponential factor In A is 39.99 s(-1). The thermodynamic parameters, Gibbs energy (Delta G(not subset of)), enthalpy (Delta H(not subset of)), and entropy (Delta S(not subset of)) of activation, at the peak temperatures were also calculated. The heat capacity of [Ho(BA)(3)phen](2) was measured by differential scanning calorimetry (DSC) over the temperature range from (254 to 470) K. In addition, the values of the experimental heat capacities were fitted to a polynomial equation with the least-squares method.