The lifetime of the lowest excited singlet state of carbonyl-containing carotenoids typically depends on the polarity of the solvent, an effect that has been attributed to the presence of an intramolecular charge transfer (ICT) state. The nature of this ICT state has yet to be clarified. In the present work, steady-state and ultrafast time-resolved optical spectroscopic experiments have been performed on peridinin and three synthetic analogues, C-33-peridinin, C-35-peridinin, and C-39-peridinin, which have different extents of pi-electron conjugation. Steady-state absorption at cryogenic temperatures revealed new absorption bands on the long-wavelength side of the strongly allowed S-0(1(1)A(g-)(-)) (->) S-2 (1113) transition that can be assigned to So (1(1)A(g)) -> Si (2(1)A(g)(-)) absorption. Analysis of the time-resolved absorption and fluorescence data sets revealed that the influence of polarity of the solvent on the excited state lifetime is unique for each molecule, leading to subtle differences in the values in highly polar solvents. Measurements in the most polar solvent, acetonitrile, demonstrated that the ICT state lifetime is shortest at 6.4 Ps for C-39-peridinin and gradually increases as the extent of pi-electron conjugation decreases, becoming 10.6 Ps for C-33-peridinin. This suggests that the energy of the ICT state is dependent on the number of conjugated carbon-carbon double bonds.