The clay composite and production process of fired clay bricks are essential for the sustainability of clay bricks. The aim of this study was to investigate the physical and mechanical properties of fired test briquettes due to the effects of charcoal addition and firing temperature. Their characteristics were carried out with the determination by TGA/SDTA, XRF, XRD and SEM. The study yielded findings, namely, test briquettes consisting of 2.5% of charcoal additive with sizes less than 0.5 mm mixed with Hang Dong clay specimen and fired at 950 °C achieved the most desirable mechanical and physical properties of fired test briquettes because fired test briquettes were more durable, porous and stronger when compared with current commercial brick specimens that were tested. Thus, charcoal could be used as a pore former in clay body. Conclusively, the results revealed that charcoal could be regarded as a potential addition to raw materials used in the manufacturing of lightweight fired clay bricks. © 2011 Elsevier Ltd. All rights reserved.