The Ba₂(H₂TNP)₂(OH)₂(H₂O)₂］·(CH₃CH₂OH)·2.5H₂O (H₂TNP: 3,5-dihydroxy-2,4,6-trinitrophenolate) complex was prepared by mixing barium nitrate solution and sodium H₂TNP solution, which was obtained through the reaction of sodium bicarbonate and trinitrophloroglucinol. The molecular structure was characterized by using element analysis, IR analysis and X-ray diffraction. The complex 1 crystallizes in tetragonal system, space group I4(1)/amd, with crystal parameters a=19.911(3) nm,b=19.911(3) nm,c=13.265(3) nm,V=5259.0(15) nm³,Z=8, R=0.0335 with 1092 reflections. The structure consists of a barium dimmer unit held together by two oxygens bridging. Each Ba atom is 10-coordinated with eight oxygen atoms from four H₂TNP, an oxygen atom from water molecule and a coordinated hydroxy ion. In complex the metal atoms are linked via oxygen bridges to infinite networks structure. Uncoordinating water molecules and ethanol molecules are present in the cavities of the crystal structure. The thermal decomposition of the complex is studied using differential scanning calorimetry (DSC), thermogravimetry-derivative thermogravimetry (TG-DTG) and IR techniques. The final residue is BaCO₃ at 550 ℃.