The pi -radical cation as well as the dication species of a series of quinonoid pi -extended TTF have been generated by means of time-resolved and steady-state radiation chemical techniques. The spectral characteristics of the a-radical cation revealed fingerprint absorptions, which are predominantly in the red region of the spectrum (570-690 nm). The maxima vary markedly upon altering (i) the substitution pattern of the TTF rings (i.e., H, S-CH3 and S-CH2-CH2-S) and (ii) the different backbone structures (i.e., anthracene, tetracene, and pentacene). In accordance with the electrochemical studies, which give rise to a single two-electron oxidation step forming directly the pi -extended TTF dication, the pi -radical cation intermediate is short-lived and decays on a time scale of several tens of milliseconds. Clean second-order decay dynamics, indicative for a disproportionation reaction of the pi -radical cation into the corresponding dications, govern the instability of the a-radical cation. By contrast the dication species is stable without showing a significant degradation over minutes. All the generated dications show transitions that are significantly shifted to the blue (455-490 nm) relative to the a-radical cation intermediates and are dominated by the polyacenic unit.