A novel complex [Ba(5-OH-BDC)(H2O)(3)] [5-OH-H2BDC=5-hydroxyisophtalic acid] was synthesized and characterized by X-ray crystallography. The complex is Monoclinic P2(1)/c, a= 11.1069(4), b=14.8192(6), c=6.5005(2)angstrom, beta=103.465(3)degrees and Z=4, which exhibits a three-dimensional framework formed by linkage of adjacent two-dimensional (6, 3) layers via intermolecular hydrogen bonds. The title complex has been studied by IR spectrum and TG-DTG. The constant-volume combustion energy of the complex, A,U, was determined as being (-3210.45 +/- 1.41) kJ mol(-1) by a precise rotating-bomb calorimeter at 298.15 K. The standard enthalpy of combustion, Delta H-c(m)theta, and the standard enthalpy of formation, Delta H-f(m)theta, were calculated as being (-3207.97 +/- 1.41) and (-1922.80 +/- 1.76) kJ mol(-1), respectively. A calculation model for determining the specific heat capacity of the complex with an improved RD496-III microcalorimeter is also derived. The specific heat capacity of the complex was (6158.387 +/- 0.187) J mol(-1) K-1. (C) 2006 Elsevier B.V. All rights reserved.