1,3-Diselena-2,4-diphosphetane-2,4-diselenides (RPSe(2))(2) with R = Me, Et, t-Bu, Ph, 4-Me(2)NC(6)H(4), 4-MeOC(6)H(4) have been synthesized by different methods. The insoluble compounds were investigated by (31)P and (77)Se solid-state NMR and the purity of the compounds has been checked by their CP MAS sideband NMR spectra. The structure of the investigated compounds has been confirmed by the isotropic and anisotropic values of the chemical shifts and the (1)J(P-Se) coupling constants. In addition, two new 1,2,4-triselena-3,5-diphospholane-3,5-diselenides, (RPSe(2))(2)Se (R = Me, Et), formed under similar synthesis conditions, were investigated. Their structure was derived from the (77)Se satellites (31)P solution spectra and from solid-state spectra. For (t-BuPSe(2))(2) the experimentally obtained principal values of phosphorus and selenium shielding tensors are compared with values from IGLO calculations (HF und SOS DFPT). The calculated orientations of the principal axes are discussed.