A naphthalene degrading bacterium was isolated from diesel contaminated soil in Damietta County, Egypt. It is identified as Pseudomonas aeruginosa strain EGDS2 based on classical and 16S rDNA sequence techniques. P. aeruginosa EGDS2 was highly able to degrade naphthalene in addition to benzene, toluene, catechol, and xylene. The normalize dioxygenases of P. aeruginosa EGDS2 responsible for naphthalene degradation was optimized for producing the maximum activity. The results revealed that the maximum dioxygenases activity was after 48 hours at pH 9.0 and 30oC. The best nitrogen source was sodium nitrate, and 7g/l of naphthalene was the optimum concentration for highest dioxygenases activity. The promising yield of dioxygenases of P. aeruginosa EGDS2 makes this isolate very useful for bioremediation of aromatic hydrocarbon pollutants.