Two crystalline modifications (Ia and Ib) of the polynuclear thallium (I) O,O′-dicyclohexyl phosphorodithioate complex [Tl{S2P(O-cyclo-C6H11)2}] n have been synthesized and characterized by CP/MAS NMR (13C, 31P). From full 31P CP/MAS NMR spectra, the χ2 plots were constructed to calculate the 31P chemical shift anisotropy 31P - δaniso = (δzz - δiso) and asymmetry parameters η = (δ yy - δ xx )/(δ zz - δiso). The data obtained for the O,O′-dicyclohexyl phosphorodithioate (Dtph) groups (in both modifications) are evidence that the 31P chemical shift tensors are intermediate between rhombic and axially symmetric. However, whereas the rhombic component dominates for Ia, the tensor for Ib is close to axially symmetric (for δ zz < δ yy ≈ δ xx ). The same pattern of the MAS spectra corresponding to negative δaniso (δ zz < δ yy < δ xx ) points to a bridging or terminal/bridging coordination mode of the Dtph groups. X-ray crystallography shows that complex Ib has a polynuclear structure (of the chain polymer type). The chains are composed of alternating structurally nonequivalent noncentrosymmetric binuclear molecules [Tl2{S2P(O-cyclo-C6H11)2}2]. All Dtph ligands have the terminal/μ3-bridging coordination mode.