The aerobic cometabolic chloroform (CF) degradation by butane-growing biomasses was investigated in slurry microcosms. The lag-time for the onset of butane utilization by the indigenous biomass of the studied sandy soil was less than 2 weeks in all the experimental conditions tested. The shortest lags were obtained in the absence of CF. The lag-time for the onset of CF depletion was strongly affected by temperature, with no CF degradation after several weeks in the tests conducted at 15 degrees C. Bioaugmentation treatments performed with two types of butane-utilizing inocula led to a marked decrease of the butane lag-time, even at the smallest concentration of augmented bacteria tested (3.5 x 10(3) CFU/mL(aq.phase)). Tests of prolonged CF degradation in the absence of butane were satisfactorily simulated with a Monod-type kinetic model. Estimates of the minimum butane/CF molar ratio required to sustain CF cometabolism varied from 2.0 to 3. 1. (c) 2007 Elsevier Ltd. All rights reserved.