Electrolytic capacitors are used in several applications rang- ing from power supplies on safety critical avionics equipment to power drivers for electro-mechanical actuators. This makes them good candidates for prognostics and health management research. Prognostics provides a way to assess remaining use- ful life of components or systems based on their current state of health and their anticipated future use and operational con- ditions. Past experiences show that capacitors tend to degrade and fail faster under high electrical and thermal stress condi- tions that they are often subjected to during operations. In this work, we study the effects of accelerated aging due to thermal stress on different sets of capacitors under different conditions. Our focus is on deriving first principles degra- dation models for thermal stress conditions. Data collected from simultaneous experiments are used to validate the de- sired models. Our overall goal is to derive accurate models of capacitor degradation, and use them to predict performance changes in DC-DC converters.