Publisher Summary Thermogravimetric analysis (TGA) essentially uses heat to drive reactions and physical changes in materials. TGA provides a quantitative measurement of any mass change in the polymer or material associated with a transition or thermal degradation. TGA can directly record the change in mass due to dehydration, decomposition, or oxidation of a polymer with time and temperature. TG curves are characteristic for a given polymer or compound because of the unique sequence of the physicochemical reaction that occurs over specific temperature ranges and heating rates and are a function of the molecular structure. The changes in mass are a result of the rupture and formation of various chemical and physical bonds at elevated temperatures that lead to the evolution of volatile products or the formation of heavier reaction products. TGA is also used to estimate the flame retardancy of polymers, as enhanced flame retardancy is often paralleled by increased amounts of residual char at high temperature. This chapter describes TGA in detail. It illustrates its theory, qualitative identification, compositional analysis, applicability, accuracy and precision, safety precautions, apparatus, and procedure.