Coal ash is a residue which was produce during the combustion of coal. Coal fly ash (FA), coal bottom ash (CBA) and boiler slag was primarily produced from the combustion process. Unfortunately, the existences of metallic elements in CBA cause the limitation to use CBA in industries. Extensive researches have been carried out to reduce heavy metal element in CBA. From previous studies, the strong acid leaching treatment was carried out to remove metallic impurities in CBA. The usage of strong acid could significantly hazardous to human and environment. In this study, the leaching process was done by replacing the usage of strong acid with citric acid which acted as weaker acid. Experimental result shows that the acid leaching treatment has potential to be used in reducing metallic elements in CBA under optimum solution temperature of 400C with 4 acid concentration at 60 min reaction period. The characteristic of CBA was also determined by comparing the SEM, particle distribution, specific gravity, water content and setting time of raw CBA with treated CBA. © 2018 Construction Research Institute of Malaysia.All right reserved.