3-Methylfluoranthene undergoes nitration at the 2-, 4-, and 8-positions in yields of ca. 20, 20, and 55%, respectively. A fourth isomer (probably the 10-nitro-isomer) was detected by gas chromatography. 3-Methyl-1-, 2-, 4-, 8-, 9-, and 10-nitrofluoranthenes have been synthesised. Dinitration of 3-methylfluoranthene gives the 4,8-dinitro-derivative. Loss of OH in the mass spectrometer seems to be characteristic