The transition to cleaner, more efficient and longer-endurance aircraft is at the forefront of research and development in air vehicles. The focus of this research is to experimentally evaluate hybrid propulsion and energy harvesting systems in unmanned aerial vehicles (UAVs). Hybrid systems offer benefits over conventional gasoline and electric systems including lower environmental impacts, reduced fuel consumption, redundancy, and distributed propulsion. Additional energy efficiency can be achieved by harvesting some of the thermal energy of the exhaust gases. The development and experimental evaluation of a hybrid propulsion UAV was carried out at the University of Victoria Center for Aerospace Research (UVIC-CfAR) in the framework of the Green Aviation Research & Development Network (GARDN) grant. The work involved the development of a framework to evaluate UAV hybrid propulsion efficiency, and to predict the amount of power harvestable from thermoelectric generators (TEGs). The objective was to combine all of the components into a modular test bench that will allow the performance of the parallel hybrid system to be characterized and compared with theoretical results. Several experiments were performed to collect performance data of various components including a triple-TEG system connected to an engine, and system variables were modified to simulate flight profiles.