The biotransformation of explosives has been investigated by many researchers. Bioremediation of soil and water contaminated with hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) is becoming the method of choice for clean-up of a variety of sites. In this study, we investigated biotransformation of RDX in the presence of barium. Ba is a metal commonly found in combination with RDX at sites requiring remediation. RDX was biotransformed by both a consortium of bacteria and an isolate from the consortium under anoxic conditions using a rich medium. However, Ba inhibited cell growth under both aerobic and anoxic conditions and slowed biotransformation rates by 40%. RDX and Ba inhibited growth of the isolate more than growth of the consortium. An additive inhibition model is proposed that accurately predicts the reduced growth rates observed.