Two strains of soil bacteria were isolated in selective trichloroacetate medium. Both strains grew feebly in all media and were of doubtful systematic position although possibly related to Arthrobacter. Trichloroacetate and its theoretical dehalogenation product oxalate could serve as carbon sources, the former under release of the halogen in ionic form. Also a few other chloro-aliphatic acids could be utilized, although this was not always accompanied by a corresponding halogen release. Amino acids were stimulatory and glucose inhibitory to the dehalogenation process. One strain was most active on trichloroacetate at approx. neutral reaction and the other at pH 4–5. Neither strain was active at pH above 9. Trichloroacetate could be attacked in a reducing (thioglycollate) medium but not under wholly anaerobic conditions.