Abstract Fly ash can be used as adsorbent, because it is cheap and effective to absorb the waste in the aquatic environment. Thus, 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. Pure fly ash was used to adsorb Hg and Pb in aqueous solution, but the adsorption capacity for Hg quite low at 17%, so it needs to be added with chitosan. Chitosan is a membrane that can be bonded with glutaraldehyde cross the amino group (-NH2). Crosslinking occurs can form pores that can enhance the adsorption properties. In this study applied fly ash as adsorbent Hg2+ in the form of fly ash composite pellet-chitosan crosslinked with glutaraldehyde. Before it was made into a composite pellets, fly ash first activated with H2SO4. The results showed that the fly ash can be in composite with chitosan gel after going through the process of physical-chemical activation that can be formed into adsorbent pellet / granule. Adsorption of Hg 2+ in solution using fly ash-chitosan granules optimum fly ash mass 4 g, pH 6 and the stirring speed of 180 rpm in the can adsorption capacity amounted to 89.53%. Model adsorption isotherm is followed Langmuir adsorption isotherm with a value of R 2> 0.998 and adsorption capacity for metal ions Hg at 0.9984 mg g -1.