This paper examined the removal efficiency of phenol from aqueous solution using a suspended culture of Pseudomonas putida (ATCC 3180) or the activated carbon on which the microorganism was immobilized. The kinetics of phenol degradation by immobilized and pure cells was studied. Experiments were performed at various phenol concentrations (0.1-0.4 g/L), pH, temperature (30-36 degrees C), and concentrations of glucose (0.5-0.7 g/L) and (NH4)2SO4 (0.5-0.7 g/L). The presence of activated carbon markedly enhanced the degradation efficiency, showing its ability of protecting microbes from confronting shock loads of organic pollutants. Degradation rate increased with increasing substrate concentration and decreased after reaching a maximum, indicating substrate-inhibition kinetics. In addition, the degradation rate for immobilized cells was much higher than that of free cells. The inhibition effect for phenol degradation was described by the Andrews model. The kinetic parameters were also determined.