The stability of adsorbed mercury on activated carbon (AC) is very important for avoiding reemission. Based on research concerning the stability of mercury on the AC relative to leaching and thermal desorption, our conclusions are as follows. Leaching tests show that mercury appears to be very stable on the AC. The Hg concentration in the leachate is much lower than the TCLP safety limit of 0.025 mg/l. Leaching time and liquid to solid (L/S) have some influence on the leaching results, but the influence is far less than which leads the Hg concentrate to exceed the safety limit. Leaching tests for mercury at lower and higher pH are aggressive compared with the neutral pH test. There is much more mercury released from the AC at longer heating time for mercury. At the same time, it seems that the stability of adsorbed original Hg-o on the AC is stronger than that of adsorbed original Hg2+. (C) 2005 Elsevier B.V. All rights reserved.