Kinetics of the thermal decomposition of un-irradiated (pristine) and pre-gamma-irradiated hydrated gadolinium acetate was studied within the temperature range (603-623 K) and in air using isothermal and dynamics thermogravimetric techniques. The data were analyzed using various solid-state reaction models. Integral method using Coat-Redfon equation was applied in dynamic data analysis. The results showed that the kinetic of isothermal and non-isothermal (dynamic) decomposition for acceleratory stage was governed by phase boundary process. The activation energies for pristine and pre-irradiated samples were calculated and the results of the isothermal and dynamic decomposition integral methods were compared and discussed. Thermodynamic values of the main decomposition process were calculated and evaluated.