Abstract Nitroreductase enzymes generally catalyze the reduction of nitroaromatic compounds to the corresponding amines. In contrast, ferredoxin NADP oxidoreductase (FNR), glutathione reductase, xanthine oxidase, and cytochrome c reductase catalyze the NADPH dependent elimination of the nitramine nitro group from 2,4,6-trinitrophenylmethylnitramine to form N-methylpicramide (NMP). Nitrite elimination was inhibited under aerobic conditions. Our results suggest that under aerobic conditions, tetryl is enzymatically reduced to the nitroanion radical which is then involved in the reduction of molecular oxygen. Under anaerobic conditions, the radical is reduced to NMP and nitrite is eliminated.