The production; testing; use and disposal of explosives have extensively contaminated the soil and water at a large number of sites. Several laboratory and field studies have indicated that explosives are toxic to a number of organisms; including humans; in relatively low amounts. There is an urgent need for simple; cheap and effective techniques which can degrade explosive compounds in soil and sludge in an ecologically sound manner. In the present study; a two-step microbiological method was developed where explosive compounds were degraded under shifting anaerobic and aerobic conditions. The method was optimized in a small-scale bioreactor where TNT was mixed with soil; water and substrate and subjected to continuous stirring. For the first 8 days; anaerobic conditions were applied to the bioreactor and for the remaining 12 days; aerobic conditions were applied. Preliminary results show that 75% of the TNT was degraded after four days. The conclusion from the study is that TNT is effectively degraded by the bioreactor technique; and the efficiency can probably be even more improved by certain modification measures.