1.For bromomethyldimethyl- and iodomethyldimethylphosphine oxides a relationship between SSCC of methylene signals and conformation composition has been shown and the parameters for separate conformers have been estimated on the basis of PMR spectra and available data on IR spectra.2.The three-dimensional structure of more complex molecules has been identified. A pronounced tendency towards decrease of the weight of conformers with trans arrangement of several carbon-halogen bonds in the series Cl, Br, and I derivatives was observed.