New metal(II) complexes with empirical formulae Co(ibup)2·4H2O, Cd(ibup)2·3H2O, Co(nap)2·H2O, Cd(nap)2·3H2O (where ibup=(CH3)2CHCH2C6H4CH(CH3COO−) and nap=CH3O(C10H6)CH(CH3COO−)) were isolated and investigated. The complexes were characterized by elemental analysis, molar conductance, IR spectroscopy
and thermal decomposition. The thermal behavior was studied by TG, DTG, DTA methods under non-isothermal conditions in air
atmosphere. The hydrated complexes lose water molecules in first step. All complexes decompose via intermediate products to corresponding metal oxides CoO and CdO. A coupled TG-MS system was used to detect the principal
volatile products of thermolysis and fragmentation processes of Co(nap)2·H2O. The IR spectra of studied complexes revealed also absorption of the carboxylate group. Principal concern with the position
of asymmetric, symmetric frequencies. The value of their separation allow to deduce about type of coordination these groups.