Electrolytic respirometry was utilized to determine the biodegradation kinetic parameters of five volatile aromatic organic compounds: benzene, 1,2-diclorobenzene, 1,3-dichlorobenzene, 1,4-dichlorobenzene and 1,2,3-trichlororbenzene. A protocol developed earlier was modified to accommodate the volatile characteristic of the test compounds. Specifically, a model used in data analysis was modified using Henry’s law constant to incorporate the effect of partitioning of a volatile substrate between the gaseous and liquid phases in a batch reactor. Similar kinetic parameters were obtained for benzene and its four chlorinated analogs. Substrate inhibition was observed in the case of 1,3- and 1,4-dichlorobenzene and intermediate product inhibition was observed in the case of 1,2-dichlorobenzene. In addition, all chlorinated benzenes exhibited complete toxicity about certain threshold concentrations.