PS/Ag microspheres were prepared by electroless silver plating on PS microspheres. SEM, EDS, and XRD approved the successful formation of silver coatings on PS microspheres. The thermogravimetric analysis was studied using a TGA system. The Ozawa and Coats-Redfern methods were exploited to calculate activation energy and determine thermal decomposition mechanism. The thermal decomposition mechanism of pure PS microspheres was also investigated to draw comparisons with the mechanism of PS/Ag microspheres. It has been found that the thermal decomposition mechanism of PS/Ag microspheres and PS microspheres were both A 2 model. The activation energy of PS microspheres and PS/Ag microspheres is 76.76 kJ/mol and 78.61 kJ/mol, respectively.