Through the development of 35 spaceflight payloads during the last ten years, BioServe Space Technologies has gained valuable practical experience in developing thermal control systems for the microgravity environment. Design constraints imposed by NASA, such as limited power availability, limited material selections, and limited acoustic emissions, coupled with the design constraints imposed by the functional requirements of each payload, impact spaceflight designs in a manner that requires a high degree of optimization. BioServe payloads typically employ thermoelectric coolers (TEC's), air and liquid heat exchangers, a variety of insulation materials, several types of fans and blowers, and various control strategies in order to achieve the desired thermal environment. In the present work methods of selecting thermal system components are discussed. In addition the integrated solution utilized in the Plant Generic Bioprocessing Apparatus (PGBA) on STS-77, STS-83 and STS-94 is presented in detail.