The development of microbore packet-column supercritical fluid chromatography/atmospheric pressure chemical ionization mass spectrometry (SFC/APCI-MS) for the analysis of polycyclic aromatic compounds (PAC) is described. The SFC system was coupled to the mass spectrometer using an improved interface designed to accommodate commercially available fused silica restrictors. The atmospheric pressure chemical ionization characteristics of PAC are discussed and the use of chemical ionization reagents to modify the type of spectra obtained is described. With selected-ion monitoring techniques the interface provided detection limits in the low picogram range for individual PAC standards. Using a photoionization detector for the off-line optimization of chromatographic conditions, SFC/APCI-MS was applied to the analysis of complex mixtures of PAC in coal tar and tar sand oil extracts. Tandem mass spectrometry was used to provide structural information.