Toxic metals, such as arsenic, selenium, mercury, chromium, lead, and cadmium, are present in coals and in many municipal and industrial wastes. This paper is concerned with the partitioning of these metals during combustion, and with the mitigation of their effect on the environment using high temperature sorbents. The partitioning of arsenic and selenium during coal combustion in a 17 kW laboratory down-fired furnace is discussed, and appropriate mechanisms identified. Second, the speciation of mercury and chromium during combustion is addressed, through special experiments on an 82 kW refractory-lined combustor. Third, experimental results on the sorption of individual and multiple metals on sorbents are presented. These sorbents were kaolinite and lime, and were injected directly into flue gas containing lead and cadmium, which had vaporized in the main flame. Results suggest that toxic metals from coal and waste combustion can interact with lime and kaolinite sorbents and that, for some multiple metal mixtures, designer sorbents containing calcium, aluminum, and silicon might be useful to capture them and render them environmentally benign.