The objective of this study were recycling of rice husk, rice husk ash, bagasse and bagasse ash waste to improve properties of lightweight clay bricks. The amount of rice husk, rice husk ash and bagasse ash waste added to lightweight clay brick were varied by 10, 20, 30, 40 % by weight, the amount of bagasse added to lightweight clay brick were varied by 5, 10, 15, 20 % by weight and variation of firing temperature by 700, 800, 900, 1000 oC. The results showed that more content of rice husk, rice husk ash, bagasse and bagasse ash waste was added, the higher values of porosity and water absorption was observed, in contrast to the reduction of thermal conduction and bulk density. The increase in firing temperature affected the decrease of porosity and water absorption, for rice husk added 20% and firing temperature 1000 oC the best properties as 1.19 g/cm3 of bulk density, 7.26 MPa of compressive strength, 0.51 W/mK of thermal conductivity, and 21.0 % of water absorption, for rice husk ash added 10% and firing temperature 900 oC the best properties as 1.20 g/cm3 of bulk density, 5.97 MPa of compressive strength, 0.43 W/mK of thermal conductivity, and 20.59 % of water absorption, for bagasse added 10% and firing temperature 1000 oC the best properties as 1.11 g/cm3 of bulk density, 8.14 MPa of compressive strength, 0.43 W/mK of thermal conductivity, and 20.60 % of water absorption, for bagasse ash added 20% and firing temperature 1000 oC the best properties as 1.2 g/cm3 of bulk density, 9.20 MPa of compressive strength, 0.45 W/mK of thermal conductivity, and 21.90 % of water absorption
