Stack emissions from an Entech Thermal Oxidation demonstration plant were measured during three test burns of ACRO drill casing fluid, mixed with municipal trash, plastic materials, tires, and used Hypalon liner material. The quantity of material burned for each tests varied form 1000 to 1450 lb. Five particulate measurements were taken for the three burns:0.063,0.013,0.0061,0.0131, and 0.0032 grains per dry standard cubic feet (dscf), 12% CO2 basis, including the backhalf. The one high measurement (0.063 gr/dscf) was taken during a period when an upset condition occurred, the particulate consisting mostly of soot. Normal CO emissions were less than 1 part per million (ppm) by volume, except for higher readings at the start of a burn or during brief upset conditions. Upset conditions occurred when the propane supply was interrupted to the secondary combustion unit or when the gas flow from the primary to the secondary combustion unit was disturbed (e.g., opening the primary combustion unit door during windy weather). HCL emissions varied from 1 to 30 ppm (0.004 to 0.086 lb/hr). Sulfur dioxide emissions were generally less than 5 ppm. NOx emissions varied from 22 to 115 ppm ( average 67 ppm). Temperatures in the secondary combustion unit were 1600 to 1850 F (870 to 1010 C). The gas detention time in the secondary chamber at 1800 F (982 C) and 700 scfm was 0.6 seconds. No dioxins (2,3,7,8-TCDD) were detected in XAD-2 resin traps used to sample the stack gas (limits of detection less than 1 nanogram per cubic meter). The ash passed the EPA Toxicity Characteristic Leaching Procedure test for determining whether or not the material was hazardous. The highest barium concentration in the TCLP leachate of five ash samples tested was 1.32 mg/L. One measurement of particulate barium in the stack exhaust was 0.008 milligrams per dry standard cubic meter.