To confirm performance assessment inputs for the Saltstone Facility at the Savannah River Site (SRS), a series of experiments were performed to examine the removal of Ra and Th by monosodium titanate (MST) and modified MST (mMST). The solubility of Th in the simulated high-level waste solutions was found to be extremely low; therefore, its removal by MST could not be measured. Radium was rapidly removed from the high-level waste simulant by both MST and mMST.