The kinetic parameters of the naphthalene degradation process performed by indigenous and introduced microorganisms were studied in soil model systems. The introduction of active naphthalene-degrading strains Pseudomonas putida BS3701 and G7 in soil model systems accelerated the naphthalene destruction process by a factor of three to four. Moreover, the addition of salicylate (0.1 mg g(-1) dry soil) to the systems containing the introduced microbial strains again doubled the rate of the naphthalene degradation process. To provide a quantitative assessment of the naphthalene biodegradation process, a mathematical model describing the bacterial growth, the consumption of the naphthalene, the production and subsequent consumption of naphthalene cleavage products, and the consumption of organic soil substances in soil model systems was developed. An approach for assessment of the degradation efficiency of low solubility polycyclic aromatic hydrocarbon provided by bacteria of genera Pseudomonas and Burkholderia in soil was suggested. The approach will enable comparison and selection of the most active degraders, which have the potential for application in biotechnologies for cleaning of soils contaminated by polycyclic aromatic hydrocarbons. (c) 2005 Society of Chemical Industry.