To examine certain aspects of coal tar composition, we have pyrolyzed acid-washed Yallourn brown coal under nitrogen at temperatures of 600 to 1000 °C in a fluidized-bed reactor. Analysis of the product tar by reverse-phase high-performance liquid chromatography with diode-array ultraviolet-visible absorption detection reveals that the tars are composed of a large number of polycyclic aromatic compounds, many of which are polycyclic aromatic hydrocarbons (PAH) with peripherally fused cyclopenta rings (CP-PAH). Among PAH, CP-PAH are of particular interest because of their proneness to oxidation in the environment, their relatively high biological activity, and their postulated role in soot formation. Of the 10 CP-PAH identified in our tar samples, 4 of the most abundant are acenaphthylene (C12H8), acephenanthrylene and aceanthrylene (C16H10), and cyclopenta[cd]pyrene (C18H10)-all of which have been detected previously in products of coal pyrolysis and/or combustion. The recent synthesis of several new CP-PAH reference standards, however, has enabled us to also identify, in the brown coal tars, six additional CP-PAH-cyclopent[hi] acephenanthrylene and cyclopenta[cd]fluoranthene (C18H10), dicyclopenta[cd,mn]pyrene and dicyclopenta[cd,jk]pyrene (C20H 10), benzo[ghi]cyclopenta[cd]perylene (C24H12), and cyclopenta[ bc]coronene (C26H12)-none of which has ever before been identified in coal products. The mass fractions of individual CP-PAH span a range of four orders of magnitude-from 0.000062 for cyclopenta[bc]coronene to 0.265 for acenaphthylene in the 1000 °C tar sample. Accounting for approximately one-third of the mass of the tar produced at 1000 °C, the CP-PAH yields show a monotonic increase with pyrolysis temperature-confirming that the CP-PAH are not primary products of coal devolatilization but instead result from secondary pyrolytic reactions in the gas phase. Possible reaction mechanisms are explored.