Zirconia thermal barrier coatings are now essentially limited to‘clean fuel’engines because the commonly used stabilizers for zirconia (CaO, MgO, Y2O3) react with the sulphur and vanadium contaminants contained in low quality fuel. Corrosion-resistant stabilizers for zirconia have been sought as a response to this problem, with ceria (CeO2) and, more recently, scandia (SC2O3) and india (ln2O3) being identified. This paper outlines some of the concepts, chemical reactions and thermodynamics that are involved in the development of hot-corrosion-resistant zirconia ceramics.