The complete acene series from naphthalene to anthracene, tetracene and pentacene were carbonized directly in a differential scanning calorimeter (DSC) special crucible heating up to 700 °C under autogenous pressure. In these conditions the carbonization of all the acenes was detected as an endothermal process occurring above 550 °C. The resulting carbonized acenes were studied by FT-IR spectroscopy showing a band pattern matching the spectrum of a mature coal and the unidentified infrared bands (UIBs) as well as the aromatic infrared bands (AIBs) detected in the interstellar and in certain circumstellar media. It is speculated that carbonized organic matter could be a valid model to explain the carriers of the UIBs/AIBs bands in space. Carbonized PAHs can be conceived as carbon dust grains formed under the action of shock waves, which are quite common in certain circumstellar and interstellar media.