Kinetics of phenol and benzoate degradation by Burkholderia cepacia G4 in classical batch mode of static culture were investigated over a wide range of initial substrate concentrations applied as single substrates. Due to better adaptation to changing conditions, faster degradation of both phenol and benzoate was observed when higher concentrations were used.  The results show decrease of the biomass yield coefficient, Y_X/S, from 0.83 to 0.31 g g^-1 when the initial phenol concentration was increased from 0.54 to 0.73 g L^-1, supporting the well known inhibitory effect of phenol. On the other hand, linear increasing of the yield coefficient was observed with increasing benzoate concentration. During all experiments, maximum specific substrate consumption rates, r_Smax, were reached to 0.27 g g^-1h^-1 for phenol and to 0.40 g g^-1h^-1 when benzoate was the sole source of carbon in the bioreactor. In the present study, minor inhibitory effect of benzoate was observed during their investigated concentration range.           To explain their degradation modelling, experimental data of both phenol and benzoate biodegradation were fitted using various kinetic models. The results demonstrated that the Yano and Koga equation gave the best fit, compared with the other models. It means that biodegradation of phenol and benzoate can be described by the same kinetic model. Based on the kinetic data, all experiments were not sensitive to change in the saturation constant, K_S; therefore, K_S-value was fixed at 0.042 and 0.068 g L^-1 for phenol and benzoate, respectively. After that, r_Smax and the inhibition constant, K_i, parameters were re-fitted in all experiments. In general, the kinetic parameters of both phenol and benzoate degradation were influenced by the initial substrate and bacterial cell mass concentrations, in addition to adaptation with changing in the culture conditions.