Bacteria utilizing naphthalene as a sole carbon source for growth were isolated and identified and code named as Acinetobacter calcoaceticus R-88, Pseudomonas testosteroni R-87 and Pseudomonas putida R-89. Among these isolates, A. calcoaceticus R-88 found most effective in utilizing naphthalene. The optimal pH, temperature and concentration of naphthalene was 7.0, $30^{circ}C$ and 10mM, respectively. The strain degraded naphthalene to salicylic acid as an intermediate. And the strain showed to be resistant to ampicillin, tetracyclin, chloramphenicol and kanamycin. A. calcoaceticus R-88 harbored plasmid DNA which was believed to be involved in naphthalene degradation.