Kinetics of the thermal decomposition of un-irradiated (pristine) and pre-gamma -irradiated dehydrated cobaltous acetate was studied within the temperature range (538-563 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 decomposition for acceleratory stage was governed by diffusion-controlled process while in non-isothermal (dynamic) decomposition the kinetic was controlled 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. The change in texture and crystal structure of the investigated cobaltous acetate by gamma -irradiation was studied using scanning electron microscopy and X-ray diffraction technique. Thermodynamic values of the main decomposition process were calculated and evaluated.