In this study, the thermal desorption process was used to treat a mercury-contaminated soils in Taipei. A series of bench or pilot plant experiments were also performed the optimized operation condition. The results showed that the concentrations of residual mercury in all treated soils were below 2 mg/kg, some even lower than 0.05 mg/kg. The supernatant and exhaust gas stream of the condensed desorbed mercury vapor in the remediation site were also met with the effluent standard. The total fee was estimated to be US$ 3,557,000, when treating contaminated soil leading to a unit treatment cost of US$ 834/m(3) of soil. (c) 2005 Elsevier B.V. All rights reserved.