BACKGROUND: In biological treatment of coking wastewater, phenol may decrease the treatment efficiency because of its high concentration and toxicity to microorganisms. Bioaugmentation has been regarded as a good improvement of the traditional biological treatment using isolated degrading strains. In this study, two phenol degrading strains, Pseudomonas sp. PCT01 and PTS02, were isolated and investigated for degradation ability and application to real coking wastewater treatment. RESULTS: Complete phenol degradation was achieved after 18 h inoculation in medium containing 229-461 mg L(-1) of phenol for both strains. The presence of phenol, pyridine and other compounds in mixed substrate or in coking wastewater prolonged the degradation to 20-32 h with an initial phenol concentration of 160-280 mg L(-1). The study of degradation kinetics yielded a two-stage model to describe the effect of the initial phenol concentration and inhibitory compounds on phenol degradation. The highest degradation rate constant of the second stage, 1.25 h(-1) for PCT01 and 0.75 h(-1) for PTS02, was obtained at low phenol concentration in a single substrate. CONCLUSION: It was found that both strains could degrade phenol effectively and maintain their phenol degradation ability in coking wastewater, and therefore could be used for bioaugmentation treatment of coking wastewater. (C) 2011 Society of Chemical Industry