Many cook stove programs implemented in South Asia and Africa were aimed at reducing fuel wood consumption and pollutants through the use of improved cook stoves. The research work presented in this paper is focused on evaluation of improved cook stoves with respect to thermal efficiency and emission levels. Since the type of biomass fuel varies in different geographical regions, the improved cook stoves must be compatible to use different types of fuel. The present research work is aimed at evaluating three types of forced draft cook stove with two types of biomass fuels. Water boiling tests were conducted to evaluate the stove performance with respect to efficiency and fuel flexibility. The findings of the study are used to evaluate the stove's performance with respect to fuel flexibility, efficiency and user acceptance. The performance results of three types of forced draft stoves tested with fuel wood and coconut shell are presented in this research paper. (C) 2012 Elsevier Ltd. All rights reserved.