The effect of melamine polyphosphate (MpolyP) on the thermal degradation of both powder and extruded samples of polyamide 66 (PA 66), was studied using thermogravimetric analysis. The results allowed us to conclude that this analytical technique was adequate for thermal stability studies. A perfect correlation was obtained between the % of char yield and the % of flame retardant in the polymer samples. Comparable results were obtained between powder and extruded samples.