Recently, in many industrial fields, there has been a drive to replace traditional metallic components with high strength polymer composites in the interest of reducing weight. Polyamide 6,6 (PA66) is a high strength thermoplastic and the behavior can be further enhanced by the addition of reinforcing fillers. Here, PA66 matrix has been reinforced with chopped glass fiber as well as hybrid composites containing both glass fiber and rubber particles. First, a baseline characterization of the mechanical properties is presented followed by a report on the thermal transitions, melting, crystallization, and glass transition, for the composite and pure materials. It is found that the filled samples show lower degree of crystallization and that the glass filled samples show lower crystallization and melting temperatures. Additionally, it was found that the glass reinforced samples led to a decrease in the glass transition temperature (Tg) while higher testing frequencies corresponded to an increase in Tg. Finally, it was demonstrated that the glass filled compounds were able to better retain their mechanical properties at high temperatures relative to the unreinforced materials. POLYM. COMPOS., 40:3960-3970, 2019.