Organoselenium compounds have been recognized as potential therapeutic agents against several diseases. Specifically, the incorporation of selenium into natural products has been reported to produce positive synergistic biological effects. We report herein the one-pot reaction of the natural monoterpenoid (-)-carvone with selenium bromide, which yields mentoselenophenone 1, together with minor amounts of phenols 2 and 3. A number of derivatives of 1 have also been prepared: the α,α dimer 6, oxime 7 and its Beckmann rearrangement product lactam 8. All except lactam 8 showed antioxidant GPx-like activity, with dimer 6 being the most active compound, followed by phenol 2 and oxime 7.