Pseudomonas sp. strain DCA1, which is capable of utilizing 1,2-dichloroethane (DCA) as sole carbon and energy source, was used to oxidize chlorinated methanes, ethanes, propanes, and ethenes. Chloroacetic acid, an intermediate in the DCA degradation pathway of strain DCA1, was used as a co-substrate since it was readily oxidized by DCA-grown cells of strain DCA1 and did not compete for the monooxygenase. All of the tested compounds except tetrachloroethylene (PER) were oxidized by cells expressing DCA monooxygenase. Strain DCA1 could not utilize any of these compounds as a growth substrate. Co-metabolic oxidation during growth on DCA was studied with 1,2-dichloropropane. Although growth on this mixture occurred, 1,2-dichloropropane strongly inhibited growth of strain DCA1. This inhibition was not caused by competition for the monooxygenase. It was shown that the oxidation of 1,2-dichloropropane resulted in the accumulation of 2,3-dichloro-1-propanol and 2-chloroethanol.