The aim of this proposal is to study the thermal evolution of the structure of two ternary ordered skutterudites, CoGe1.5Q1.5 (Q = S, Te). At room temperature, ordering of the Ge and Q atoms results in a lowering of the symmetry of the skutterudite from cubic (Im-3) to rhombohedral (R-3). The degree of ordering is dependent on the rate of cooling of the materials, suggesting that a transition to a cubic disordered skutterudite takes place at elevated temperatures. Given the small deviation of the rhombohedral angle from 90º found for these phases, high-resolution data are essential and therefore we propose to use HRPD. In addition, we are seeking to investigate ordering at the metal site for the ternary skutterudite Fe0.5Ni0.5Sb3.