Naphthalene, being a ubiquitous pollutant of the environment and a perilous material, its biodegradation has been receiving constant scientific consideration. Highly potential, naphthalene degrading bacteria were isolated from sediments of polluted Amlakadi canal, Gujarat, India. Among the isolates, Pseudomonas sp. HOB1, showed ability to degrade 2000 ppm naphthalene within 24 h. The culture exhibited potential to tolerate as high as 60,000 ppm of naphthalene. Statistical approach was used to analyze the effect of physiological parameters and initial biomass concentration on naphthalene degradation. Naphthalene degradation was found to be augmented in the pH range of 7.5-8.5. Naphthalene degradation was maximum in the temperature range of 35-37 degrees C and initial inoculum size of more than 1.8 ml of 1.0A(660). Simulated microcosm studies in the presence and absence of indigenous microflora confirmed its ability for naphthalene degradation and to colonize the soil. Pseudomonas sp. HOBI was found to be highly potent in degrading higher concentrations of naphthalene under laboratory conditions as well as in simulated microcosms. (C) 2008 Elsevier B.V. All rights reserved.