Quantitative optical absorption spectra of the cation radicals and the dications of canthaxanthin (I), beta-carotene (II), 7’-cyano-7’-ethoxycarbonyl-7’-apo-beta-carotene (III), and 7’,7’-dimethyl-7’-apo-beta-carotene (IV) in dichloromethane solution are reported. Exclusive formation of dications occurs when the carotenoids are oxidized with ferric chloride. Addition of neutral carotenoid to the dications results in equilibrium formation of cation radicals. Oxidation with iodine in dichloromethane affords only cation radicals; electrochemical oxidation under suitable conditions yields both dications and cation radicals. Values of the optical parameters depend on the nature of the oxidative medium. The oscillator strengths calculated for gas phase cation radicals and dications of I-IV using the INDO/S method show the same trend as the experimental values.