Lanthanide chalcogenolates react with either TeO(2) in pyridine or py-SO(3) in THF to give oxychalcogenido clusters. The sulfido derivatives (THF)(8)Ln(8)S(2)O(2)(SePh)(16) (Ln = Ce, Nd) are isostructural with previously reported oxoselenido compounds, and must be prepared at low temperatures to avoid the introduction of Se into the sulfide position. Analogous telluride derivatives for the early lanthanides were not obtained, but reactions of in situ prepared Ln(TePh)(3) with elemental Te and TeO(2) gave a complicated heterocluster product, with tetrametallic polytelluride [(py)(7)Ln(4)(mu(4)-Te)(mu(2)-Te(2))(2)(mu-eta(2)-eta(2)-Te(2)Te(Ph)Te(2))(TePh)] co-crystallizing with the oxotellurido compound [(py)(5)Ln(3)(mu(3)-O)(mu(2)-Te(2))(3)(TePh)] (Ln = Ho, Er). An analysis of the thermal decomposition of these compounds did not identify the oxo-containing products, with the sulfide compounds decomposing to give only Ln(3)Se(4) and the telluride compounds forming crystalline LnTe and Te metal.