Photodissociation spectroscopy is used to explore the structures of the C8H8+ and C8H9+ ions obtained in gas phase from styrene, cyclooctatetraene, and barrelene. The C8H8+ ions do not interconvert on a time scale of seconds, and the parentions of styrene and barrelene appear to retain the neutral structure, while the structure of the COT parent ion is uncertain. The C8H9+ ions obtained by H3O+ protonation all have the same spectrum, and are assigned as having the styryl ion structure. © 1979, American Chemical Society. All rights reserved.