With its non-polluting nature, unlimited free supply and worldwide availability, solar energy is a most attractive non-conventional energy source. The solar energy is used for cooking, heating, lighting, pumping, electricity generation, etc. Solar cooking is the effortless, secure and most suitable way to cook food without consuming fuels. So, many countries in the world are using different types of solar cooker. Generally, solar cooker consumes more time to cook food compared to other conventional cooking devices. In this paper, the performance of box type solar cooker is investigated using various materials to increase heat retaining capacity of the cooker and hence to minimize cooking time. Readings of temperature vs. time were taken by placing different materials like black sand, brown sand, marbles, salt, small rocks, abrus and pebbles at the base of the solar cooker. From this analysis, it was found that marbles achieve a maximum temperature of 207.8 °C in 180 min which can be helpful in reducing the time for cooking.