The flux synthesis of single crystals of the isostructural compounds tristrontium zinc platinum hexaoxide, Sr3ZnPtO6, and tristrontium cadmium platinum hexaoxide, Sr3CdPtO6, is reported. The compounds adopt the pseudo-one-dimensional rhombohedral K4CdCl6 structure type, and feature chains of face-shared distorted ZnO6 or CdO6 trigonal prisms and PtO6 octahedra, surrounded by columns of Sr2+ ions. All transition metals are located on the threefold axis of symmetry, while the Sr2+ cations lie on twofold axes. Formula: Sr3ZnPtO6 and Sr3CdPtO6