Abstract There has been a considerable recent interest in the design, development and testing of various types of solar cookers like box type, concentrator type and oven type around the globe. Out of these, box type solar cookers have so far been disseminated at the mass level which is the simplest in terms of operation and fabrication and the temperature of around 100 °C is achieved. This range of temperature is suitable for cooking by boiling, which is prevalent in the most parts of India. However, in spite of having these desired features, such cooker may either fail to cook or take a longer time to cook full load of food. The design parameters of solar cooker are among the several other important parameters that influence its thermal performance. In order to analyze the thermal performance of a box-type solar cooker in a better qualitative manner, it is therefore necessary to have the knowledge of design parameters, optical efficiency and heat capacity of the cooker to provide a basis for the selection of proper materials for its construction. This study deals with a test procedure to determine these parameters using the experimentally obtained F2 data for different load of water and to apply the proposed procedure to predict the heating characteristic curves and to validate the proposed methodology by comparing the predicted values with those obtained experimentally.