The Environmental Protection Agency (EPA), under the requirements of the Clean Air Acts Amendments (Public Law 101-549), evaluated the hazardous air pollutants emitted by coal-fired power plants. In December 1997 and February 1998, they reported their findings to Congress. The report identified mercury as the air toxin of primary concern from coal-fired power plant emissions. As a result, EPA was required to make a determination on whether to regulate the emission of mercury from coal-fired power plants and did so on December 14, 2000. The EPA will promulgate mercury control regulations by December 2004 and coal-fired power plants will be required to be in compliance by 2007. Several government and private organizations have initiated the evaluation and development of options for the removal of mercury from flue gases. The major efforts have focused on the removal of mercury from the flue gas by use of carbon-based sorbents or optimization of existing flue gas emissions control technologies to capture mercury. The utilization of carbon-based sorbents is effective. but appears to be expensive. The use of existing emission control equipment to capture mercury is hampered by the rank of coal being used and the specific equipment available at individual plants. This will limit the effectiveness of using existing control technologies. To address the need for control of mercury emissions, Western Research Institute (WRI) initiated efforts to develop a patented (U.S. Patent No. 5, 403, 365) pre-combustion thermal process for the control of mercury emissions from low-ranked coal. The results from preliminary evaluation of the WRI technology indicate that about 70-80 Wt.% of the mercury is removed from the coal when the temperature is raised from 150 (302) to about 290 degreesC (554 degreesF). The remaining 20 wt.% of the mercury remains in the char at temperatures up to about 593 degreesC (1100 degreesF) [N. Merriam, Removal of mercury from Powder River Basin (PRB) coal by low-temperature thermal treatment, Topical Report to U.S. Department of Energy, Western Research Institute, Laramie, WY, WRI Report WRI-93-R021, 1993]. Current research efforts have focused on evaluating the effect of the principal operating parameters on the removal of mercury. The results show mercury is not evolved at temperatures below 150 degreesC (302 degreesF) and that mercury evolution reaches a constant value at 270 degreesC (518 degreesF). The mercury removal, as a function of residence time, shows an increase with increased residence time until a constant value is reached after about 4 min. The mercury removal has been shown to increase linearly with sweep gas flow rate over the range studied. This paper discusses the status of the development of this process and presents fundamental data relative to its performance on PRB coal and lignite. (C) 2004 Elsevier B.V. All tights reserved.