The thermal behavior of [Tb2(m-MBA)6(phen)2](H2O)2(m-MBA=C8H7O2, methoxybenzoate; phen=C12H8N2, 1,10-phenanthroline) in static air atmosphere was investigated by means of TG-DTG and DTA methods. The thermal decomposition of the title compound takes place mainly in two steps. The intermediate and the residue for each decomposition were identified by the TG curve. By the kinetic method of processing thermal analysis data put forward by Malek et al., it is defined that the kinetics model for the first-step thermal decomposition is SB(m,n).