The thermal degradation of bulk and miniature samples of expanded polystyrene (EPS) has been investigated in a neutral atmosphere at 800°C and by differential scanning calorimetry over a range of temperatures. The differential scanning calorimetry experiments showed that the foam volatilization temperature is significantly affected by heating rate and varies from 380°C to 470°C at heating rates from 10–60°C/min. Bulk degradation due to the 800°C heat source appeared to occur instantly as the foam pattern approached the close proximity of the heat source. The chamber pressure increased and the heat source temperature dropped during degradation. The gas yield at 800°C was determined to be about 610 cm3 (STP)/g of EPS.