This study was aimed to investigate the efficiency of phenol degradation by Pseudomonas putida entrapped within the beads prepared by chitosan crosslinked with sodium tripolyphosphate. The efficiency of phenol degradation was optimized by changing various processing parameters, such as the amount of cells, beads washing medium as well as acclimatization strategy. These entrapped cells were found to be superior to the free suspended ones in terms of improving the toleration to the environmental loadings (e.g., high pH, low ionic strength and high phenol concentration) and repeating usage for an extended period. Diffusion coefficient calculation has indicated that phenol degradation by the entrapped cells varied from the intraparticle diffusion control to the reaction control as the beads were used repeatedly. In the bead-packed column test, with the addition of hydrogen peroxide to increase the dissolved oxygen level for cell metabolism, phenol in the influent was almost completely degraded. (c) 2007 Elsevier Ltd. All rights reserved.