The squaraine dye bis[4-(dimethylamino)phenyl]squaraine gives a persistent radical cation upon one-electron oxidation in dichloromethane. In the presence of trifluoroacetic acid in high concentration (0.5-1.0 M), a second persistent radical cation is detectable upon oxidation, most likely formed by one-electron loss from a dye species protonated on one oxygen and one nitrogen. Both species were characterized by their UV-vis and EPR spectral properties.