Abstract— Developments in urban sector require to follow proper planning in every aspect to rescue causing severe environmental issues such as urban heat island thus global warming, losing the native appearance etc. Both Surface and Atmospheric urban heat island make high impacts on thermal comfort in tropical hot climates. Therefore, the selection of materials, especially focusing on outdoor paving plays a vital role with respect to the urban heat island mitigation and achieving human thermal comfort thus sustainability. Popular materials found for outdoor paving are asphalts, concrete, burnt clay bricks etc. However, there are many drawbacks of using paving blocks in outdoors as a whole, with respect to the user's thermal comfort as well as sustainability. Thereby, there is a gap of knowledge in identifying and developing thermal properties of materials used for outdoors. Accordingly, this research suggests evaluating and comparing the thermal performance of newly invented soil based material that is mud concrete paving block with selected popular paving materials used for outdoor development in Sri Lanka. Cement concrete, burnt brick, Asphalt and Mud concrete paving blocks are selected as sample materials and equal areas of each specimen were paved in an unshaded open space where direct solar radiation reaches. Secondly, the same colour was applied on the surfaces of the specimens to avoid the albedo effect. The results obtained were analyzed in terms of thermal performance. The results indicated that the material properties and their surface colour have an influence on its thermal performance. Further, results have proven that the mud concrete paving block has high potential on its thermal performance as a sustainable solution to be used in outdoor development.