Two bacterial strains were isolated from forest soil by selective enrichment of the mineral medium containing 4-nitropyrocatechol as the sole carbon and energy source. Both strains could utilize 4-nitropyrocatechol and 5-nitroguaiacol. Degradation of 5-nitroguaiacol and stoichiometric release of nitrites was measured during its degradation both in growing culture and for resting cells. Both strains were unable to degrade other nitroaromatic compounds such as 4-nitroguaiacol, 2-nitrophenol, 3-nitrophenol, 4-nitrophenol, 2,4-dinitrobenzoic acid, 4,5-dimethoxy-2-nitrobenzoic acid and 2,3-difluoro-6-nitrophenol. One strain was identified as Rhodococcus opacus and the second one as Rhodococcus sp.