To explore the potential of Pr7O12 in a biphasic oxygen buffer in automobile exhaust control systems, thermodynamic data for Pr7O12 are required. Since there is no information on Pr7O12 in thermodynamic data compilations, its Gibbs energy of formation has been determined relative to that of Pr2O3 as a function of temperature in the range from 850 to 1200 K using a solid-state electrochemical technique. The standard molar Gibbs energy of formation of Pr7O12 from elements can be represented by two equations. In the range from 850 to 1068 K, Delta G(f)degrees (J mol(-1)) = -6454317 + 1085.52 (T/K). From 1068 to 1204 K, Delta G(f)degrees (J mol(-1)) = -6467695 + 1097.77 (T/K). (C) 2019 Elsevier Ltd.