A strain of Nocardia alba and several types of Pseudomonadales from soil aerobically decompose o-nitro-phenol, m-nitro-phenol, p-nitro-phenol, 2,4-dinitro-phenol, o-nitro-benzoic-acid and p-nitro-benzoic-acid using these compounds as sole C- and N-source. The pathway of oxidative decomposition of the nitro-compounds was studied by Stanier''s method of simultaneous adaptation. Oxhydroquinone takes a central position in these metabolic pathways.