Heavy metal contamination often accompanies pollution with petroleum oil derivatives. Metal ions may considerably affect the process of hydrocarbon biodegradation. The results obtained for bacterial strains Gordon ia a/kanivorans S7 and Pseudom on as fluorescens SL3 indicated the limitation of cell growth and reduced ability of degradation of petroleum oil hydrocarbons in the presence ferric ions in the range of 15-100 mg Fe/dm3. However, the addition of these ions in the range of 1-7 mg Fe/dm3 might appear to be advantageous for biodegradation process. Supplementation with ferric ions in the range of 50-100 mg Fe/dm' decreases emulsifying activity of tested strains. The excess of these ions is accumulated in the bacterial cells.