Four titanate ceramics were characterized and tested. These ceramics were similar to those proposed for Pu disposition, with Ce as a surrogate for Pu. The baseline ceramic contained Ti, U, Ca, Hf, Gd, and Ce, and was made up of only four crystalline phases: pyrochlore, zirconolite, rutile, and brannerite. The three other ceramics contained different amounts of impurities that are expected in the feed. Impurities are defined as any element other than Ti, U, Ca, Hf, Gd, and Ce. The ceramics that contained impurities contained different phases than the baseline. The addition of impurities led to the absence of brannerite and the presence of amorphous silicate, Ca-Al-Ti, and perovskite phases. The results from 3 day, 90°C MCC-I tests with impurity ceramics were significantly different than the results from tests with the baseline ceramic. Overall, the addition of impurities to these titanate ceramics altered the phase assemblages, which in turn, affected the corrosion behavior.