The TbIII compound [Tb(tci)(H2O)]n·n(DMF) (1) [H3tci = tri(2-carboxythyl)isocyanurate, DMF = N,N′-dimethylformamide] was synthesized by the reaction of terbium oxide, H3tci, and two drops of concentrated nitric acid in the presence of DMF and H2O. Single crystal X-ray analysis reveals that it features a three-dimensional (3D) framework based on infinite –Tb–COO–Tb– chains. The tci ligand in 1 links six different TbIII ions with its two carboxylate groups in μ2-κ1O;κ2O,O′ mode and the third in μ2-κ1O;κ1O′ mode. Thermal analysis reveals that it remains high thermal stability until 390 °C. Luminescence investigation shows that it emits characteristic green light of TbIII ions.