The¹H and²H NMR spectra were taken for mixed monocrystals of light (C₄H₈SO₂) and perdeuterated sulfolanes in the plastic phase. CNDO/2 and INDO calculations were carried out for the sulfolane molecule to give the geometrical parameters, which strongly affect the molecular energy. The other parameters, which characterize the molecular configuration and intramolecular motions, as well as the orientational order matrix were determined by analysis of the¹H and²H NMR spectra.