Use of fluorescence spectrometry as a qualitative analytical technique in the characterization of high-boiling petroleum distillates is reported. Examples of fluorescence emission and fluorescence excitation spectra obtained from compound types in 400 deg to 500 deg c distillates are shown. Among the compound types identified were carbazoles, 11h-benzo[a]carbazoles, 7h- benzo[c]carbazoles, perylenes, coronenes, benzo[ghi]perylenes, and chrysenes. Fluorescence and excitation peak maxima of 35 aromatic model compounds are reported. The separation scheme which produced samples suitable for fluorescence analysis involved the use of ion exchange chromatography, gel permeation chromatography, and thin- layer chromatography.