The 1H NMR spectra of the nitrofluoranthene isomers are presented to allow gas chromatographic analysis of environmental samples suspected of containing nitrofluoranthenes. The mutagenic isomers 1-, 2-, 3-, 7-, and 8-nitrofluoranthene and 1,2- and 1,3-dinitrofluoranthene and a nonmutagenic analogue, 1-phenyl-4-nitronaphthalene, have been studied by using nuclear Overhauser effects and 2D shift-correlated 1H NMR spectroscopy. The X-ray crystal structure of 1-phenyl-4-nitronaphthalene is also reported. Reduction potentials and coplanarity of the nitro group have been used to correlate the mutagenicity of nitrated polycyclic aromatic hydrocarbons (nitro-PAH) measured by the Ames assay, but our data suggest that these parameters are not sufficient for the prediction of mutagenic potency in the nitrofluoranthene series.