Intact cells, disrupted cells (obtained by sonication of the biomass), and crude extracts of Pseudomonas putida strain 109 were shown to have similar dehalogenase activity. An immobilized preparation of dehalogenase dehalogenase on celite retained its activity in polar organic solvents such as dimethyl sulfoxide (DMSO) and dimethylformamide. The nucleophilic substitution of the halogen in 2-bromopropionic acid by water proceeded in the above-mentioned solvents only if at least stoichiometric amounts of water were present in the reaction mixture. The stereochemistry of the product obtained from racemic 2-bromopropionic acid by the action of celite-immobilized disrupted cells of P. putida str-ain 109 in DMSO differed from that of the enantiomer obtained in an aqueous buffer. The specificity of the enzyme was also tested on other substrates derived from 2-bromopropionic acid.