ABSTRACT Fly ash can be used as adsorbent, because it is cheap and effective to absorb the waste in the aquatic environment. In addition, fly ash has a main component in the form of silica (SiO2), alumina (Al2O3), iron oxide (Fe2O3) and a number of unburned carbon, this component has an important role in the adsorption process. Fly ash is inexpensive adsorbent, efficient, simple preparation, easy to operate and can be used to absorp heavy metal ions. Pure fly ash was used to adsorb Hg and Pb in aqueous solution, but the adsorption capacity for Hg quite low at 17%. Fly ash dust cannot be applied in the adsorption column because after a while it will form an impermeable solids. In a stirred tank will also result in problems with the fly ash material separation of the solution, so that the use of fly ash pellets in the adsorption column will not cause problems and waste water can easily seep into the column containing the pellets without the risk of clogged. In addition, the use of fly ash dust can change the pH of the waste water and become strong alkaline with a pH of more than 11 after the wastewater treated. The use of fly ash pellets only change slightly the pH of wastewater after treatment is not more than pH 8 and is still within the permissible limits. In this study, fly ash was applied as adsorbent of Hg2+ in the form of fly ash composite pellet-chitosan cross linked with glutaraldehyde. Key words: chitosan, fly ash, FTIR, Hg