Rhodococcus rhodochrous IGTS8 (ATCC 53968) was shown to be capable of utilizing 2-chloroethyl ethyl sulphide (GEES) as the sole source of sulphur for microbial growth. 2-chloroethanol and a compound tentatively identified as 2-chloroethanesulfinic acid have been detected as metabolites. This demonstrates that carbon-sulphur bonds were cleaved in GEES prior to hydrolysis of the chlorine atom. These data indicate that Rhodococcus rhodochrous IGTS8 may be useful for the biodetoxification of the chemical warfare agent mustard (2,2’ dichlorodiethyl sulphide).