Fires are responsible for the loss of thousands of lives and billions of dollars in property damage each year in the United States. Flame retardants can assist in the prevention of fires through mechanisms which either prevent or greatly inhibit flame spread and development. In this study samples of both brominated and non-brominated polystyrene were tested in the Milligram-scale Flaming Calorimeter and images captured with two DSL-R cameras were analyzed to determine flame temperatures through use of a non-intrusive method. Based on the flame temperature measurement results, a better understanding of the gas phase mechanisms of flame retardants may result, as temperature is an important diagnostic in the study of fire and combustion. Measurements taken at 70% of the total flame height resulted in average maximum temperatures of about 1656 K for polystyrene and about 1614 K for brominated polystyrene, suggesting that the polymer flame retardant may reduce flame temperatures.