The distributions of nine trace metals in flue gas particulate by particle size range were determined as part of a pilot-scale hazardous waste incineration test program. These tests were conducted in the rotary kiln incinerator system at the U.S. EPA's Incineration Research Facility in Jefferson, Arkansas. The metals (arsenic, barium, bismuth, cadmium, chromium, copper, lead, magnesium, and strontium) were fed to the kiln as part of a synthetic waste. Testing was designed to evaluate the effects of kiln temperature (varied from 816C to 927C) and waste feed chlorine content (varied from 0% to 8%) on metal distributions. Flue gas particulate samples, collected at the afterburner exit, were size-fractionated, yielding ranges of nominally less than 2 micrometers, 2 to 4 micrometers, 4 to 10 micrometers, 10 to 30 micrometers, and greater than 30 micrometers. Increasing kiln temperature from 816C to 927C caused the average distributions to shift from roughly 20% less than 10 micrometers to an average of 60% less than 10 micrometers for all metals except chromium. An increase in waste feed chlorine content from 0% to 4% caused the distributions of cadmium, copper and lead to shift from roughly 20% less than 10 micrometers to 55% less than 10 micrometers. No further effects were observed for these three metals as feed chlorine increased from 4% to 8%. For Chromium, increasing chlorine content from 0% to 4% to 8%, caused a corresponding shift of 2% to 20% to 50% in the less than 10 micrometers fraction.