Opticalresolution of racemic selenoxides, 1a, 1b, and 1c, and telluroxide 2b, possessing an 8-dimethylamino-1-naphthyl group by liquid chromatography using optically active columns afforded the corresponding enantiomerically pure stereoisomers. Absolute configurations of the optically active chalcogen oxides were assigned by comparison of their specific rotations and CD spectra with those of the sulfur