The thermal decomposition of the complex of Schiff base containing S,N-Cd-3[CH3O(O)C6H3CH = NNHC(S)NH2](4) .(CH3COO)2 . 1/2[CH3S(O)CH3]. 2H(2)O and its nonisothermal kinetics have been studied by TG and DTG. The non-isothermal kinetic data were analyzed and the kinetic parameters for the first, second and third steps of the thermal decomposition were evaluated by two different methods - differential and integral methods and tested by other methods. The most probable mechanism functions of the thermal decomposition reaction are : [GRAPHICS] are : [GRAPHICS] Fe(HOCH2CH2)(2) NH2(SO4)(2) . 4H(2)O; Fe(HOCH2CH2)(3)NH(SO4)(2) . 6H(2)O. From the X-ray powder diffraction patterns, it was concluded that the investigated compounds have different crystal structures. It was also established, from the TG curves, that they lose water at low temperature and also that the anhydrous double salts decompose at low temperature (at about 523 K).