The vapour-phase and particulate-bound Aromatic Hydrocarbons, PAHs, generated by a V6 gasoline engine working in spark-ignition (SI) and homogeneous charge compression ignition (HCCI) modes were collected and analysed. All data were obtained during steady-state, fully warmed-up operation at different engine power levels (low and medium loads and mid-speed), and two different engine operation modes (SI and HCCI). The fuel used in this study was winter grade commercial gasoline fuel. The vapour-phase exhaust gases were passed through stainless-steel cartridges containing XAD-2 resin to capture PAHs. The PAHs were extracted from the resin with dichloromethane in an ultrasonic bath, the obtained extracts were later analysed qualitatively and quantitatively by GC-MS. The vapour-phase PAHs compounds observed from HCCI mode operated in low load were Naphthalene, Acenaphthylene and Acenaphthene only, while that obtained from SI mode under low load were Naphthalene, Acenaphthylene, Acenaphthene, Fluorene, Anthracene, Phenanthrene, Fluoranthene and Pyrene. The PAHs bound to particulates were trapped by using a complex of dilution tunnels with filter papers. The soluble organic fractions (SOF) of the trapped particulates were separated from the insoluble fraction (ISF) with the help of ultrasonic elution, and analysed by GC-MS method. The most abundant PAHs detected under selected operation condition for HCCI mode was Benzo[a] anthracene, followed by Chrysene, then Pyrene and pursued by Benzo[b] fluoranthene, in SI mode under same operation condition the highest PAH detected was Benzo[a] anthracene followed by Pyrene, Benzo[b] fluoranthene and Chrysene. Probable mechanisms for the production of some of the pyrosynthetic PAH were discussed. (C) 2010 Elsevier Ltd. All rights reserved.