To utility of Esener and Monod equations was evaluated for non-steady state conditions. In the case of the reactors response to a pulse and step changes of dilution rate, a satisfactory agreement of the experimental data with the numerical both Esener and Monod models results were confirmed of the experiment. A very good agreement of experimental data with numerical solutions was observed in the case of pseudo-steady response to retrangular wave change of diluton rate. Analyzing the reactor response to the inhibitor concentration changes, a good concordance experimental data with calculated values of sudden changes was observed, and a distinct disareement in cases of pulse and step changes of the inhibitor concentration. In the reactor response to the retrangular wave change of inhibitor concentration the difference between experimental and calculated data was observed.