Thermodynamics and thermal stress analysis of thermo-electric power generator is carried out. The influence of device geometry on thermal stress, thermal efficiency and output power is examined. The finite element method is incorporated to predict temperature and stress fields in the thermo electric device. It is found that thermal efficiency improves for certain geometric configuration of the device. In this case; the maximum thermal stress developed in the pin reduces slightly indicating improved life expectation of the device. (C) 2012 Elsevier Ltd. All rights reserved.