A new chemical process has been studied to clean up a mercury-polluted soil by using acidic potassium iodide (KI) solution. A highly contaminated soil (max. 47.1 mg Hg/g) was used as a model sample. Evaluation was made on the effects of aqua regia, HCl, NaOH, Na-EDTA and KI solutions to extract mercury from polluted soil in a batch process. A mixture of 100 mM KI + 50 mM HCl (pH = 1.5) was found to be most effective. The acidic KI solution was passed through a column packed with 9.8 g polluted soil at a flow rate of 25 ml/h. After 15 fraction volumes, the mercury content decreased from 113.5 to 26.2 mg. The leachate from the column test containing HgI 2 - 4 was treated with granular activated carbon.