The removal of mercury by adsorption process using fly ash was investigated in this study. Mercury removal capacity of fly ash was performed by batch mode adsorption experiment with the effect of various parameters i.e., contact time (0.5-3.5) h, pH of 2-10, concentration of adsorbate (1, 5 and 10)
mg l-1, adsorbent dose (100-1000) mg per 100 ml solution and temperature (303, 313 and 323) K. Mercury concentration (10 mg l-1) was chosen for all parameters except adsorbent dose. The experimental data were showed that the adsorbent dose of 200, 400 and 600 mg per 100 ml were sufficient to maximum removal of mercury (98 percent) from aqueous solution of mercury (1, 5 and 10) mg.L-1 at equilibrium and 89 percent mercury was removed when concentration was 10 mg l-1 at 303K temperature. Adsorbent dose of 100 mg per 100 ml solution showed 74 percent removal of mercury for 2 hours contact time and 90 percent removal at pH 10. The experimental data were fitted with pseudo first order and pseudo second order kinetics which was proposed by Lagergreen. The value of pseudo first order rate constant, k1 is 0.697 h-1 and pseudo second order rate constant k2 is 0.135 l mg-1 h-1.