The ability of Gloeophyllum species to produce dimethoxybenzoquinones (DMBQ), particularly 2.5-dimethoxyhydroquinone (2,5-DMHQ), and oxalic acid was investigated. The involvement of these compounds, along with hydrogen peroxide and Fe(III), in 2,4,6-trinitrotoluene (TNT) degradation was examined. Salicylic acid (SA) and phenol (PH) were used as probes to trap Fenton process-produced hydroxyl radicals in several of the investigated species, All the cultures degraded SA and PH readily. A low concentration of 2,3-dihydroxy benzoic acids was detected in cultures of only two Gloeophyllum species. TNT was rapidly transformed by G. trabeum, but ring-UL-C-14-TNT was not converted to (CO2)-C-14. Mass balance studies indicated that about 74% of the radioactivity from TNT remained in the culture supernatant. Analysis of culture extracts revealed several aromatic nitro-amines and nitro-aidehydes, and their oligomeric Coupling products formed by Schiff base reaction mechanism. 2,2,6,6-Tetramethyl-1-piperidynyloxide (TEMPO), a stable free radical, Was used as a trap in in vitro reactions containing hydrogen peroxide, 2,5-DMHQ, and TNT. The coupling products of TEMPO and 2,5-DMHQ were detected, indicating semi-dimethoxy quinone radical formation. The in vitro Fenton-like reaction containing all above reactants except methoxyquinones produced degradation products from TNT similar to those extracted from G, trabeum cultures, suggesting that reduced oxygen species produced by Fenton-like reactions are involved in the transformation of TNT by brown-rot fungi such as G. trabeum.