The report gives results of investigations of adipic acid degradation to account for losses observed during earlier studies where it was used as an additive to improve SO2 scrubber performance. Bench-scale experiments identified the major species resulting from the oxidative degradation of adipic acid, which are: valeric acid, glutaric acid, CO2, CO, carbonate, methane, ethane, propane, and butane. Material balances based on various measurements--including gas chromatography, ion-chromatography, and total organic carbon analyses--indicate that all by-products were indentified in the laboratory tests: imbalances were less than 10% of the total carbon used. Field tests conducted on a prototype limestone scrubber using adipic acid additive detected only valeric acid and glutaric acid as degradation products. Scrubber sludge was shown to retain 200-500 ppm adipic acid by surface adsorption. In addition, the solids contained 300-800 ppm of occluded adipic acid when precipitated as calcium sulfite; occlusion was only 50 ppm when the solids were oxidized to gypsum.