When exposed to the Fenton oxidation process, approximately 25% of the initial TNT was mineralized and approximately 63% was converted to unknown soluble products. When exposed to Fe(0) under acidic conditions, TNT was completely reduced to unknown products, approximately 20% of which were not soluble. Reduction of TNT by Fe(0) did not occur above pH 3.0. When exposed to sulfide, TNT was reduced to a mixture of 4ADNT, 2ADNT, DA6NT and unknown soluble products. TNT and its reduction products from chemical (iron and sulfide), aquatic plant, and Clostridia systems were not mineralized by either an activated sludge culture or a mixed aerobic culture grown on anthranilic acid. Biological transformation of TNT and sulfide-reduced TNT products, however, did appear to occur in the aerobic microbial culture grown on anthranilic acid.