In an attempt to estimate the ability of cometabolic Trichloroethylene (TCE) degradation by aerobic TCE degradation bacteria, a modified competitive inhibition model of Monod kinetics into which was incorporated the effect of TCE product toxicity was applied to batch tests in serum bottles. A simulation that fit the parameters with values obtained from literature and experiments from batch tests was performed to calibrate the model for the batch tests. As a result, a good and reasonable fit was obtained between the experimental data and model predictions both for TCE disappearance with resting cells and for TCE and methane disappearance with methanotrophic mixed culture and methane gas. In the case of the soil that contained in the bottles, a reasonable explanation for TCE disappearance was also obtained by incorporating a nonequilibrium sorption model of TCE in soil into the model. This application model is expected to be useful for predicting TCE transformation in an aquifer by cometabolic degradation bacteria.