The need of energy is increasing enormously day by day and presently it is being fulfilled mostly by depleting energy resources like coal and petroleum based fuels. This situation pushes mankind to search for novel green technologies which can convert efficiently even low grade heat energy into useful energy. Thermoelectric generator (TEG) promises to be clear technology to generate electricity. TEG uses temperature gradient between source and sink to generate electricity. In this study, performance of commercially available thermoelectric module was studied using a specially designed cross flow heat exchanger. The heat exchanger was optimized previously using commercially available CFD package Ansys CFX. The efficiency of thermoelectric module was calculated by taking figure of merit and Carnot efficiency into consideration. The results indicate that the commercially available TEG used in this study, which is made of Bismuth Telluride performs efficiently at higher temperature difference and value of figure of merit is around one at maximum efficiency.