It was mathematically predicted and numerically demonstrated [Yoo and Martin, Phys. Chem. Chem. Phys. 12 (1210) 14699] that the open-circuit voltage U of a galvanic cell, involving a multinary compound with multiple ionic carriers subjected to multiple chemical potential differences, be path- and time-dependent, unlike a cell involving a pure binary or a multinary compound with a single type ionic carrier. The path- and time-dependence of U is now experimentally demonstrated with a galvanic cell, mu(O2)',mu(H2O)'vertical bar SrCe0.95Yb0.05O3-delta vertical bar mu(O2)'',mu(H2O)'' involving a proton-conducting, mixed ionic electronic conductor, e.g., SrCe0.95Yb0.05O3-delta with H+ and O2- as ionic carriers subjected to the chemical potential differences of oxygen and water. The results are compared with a cell involving a multinary Zr0.84Y0.16O1.92 but with a single type ionic carrier O2-, mu(O2)',mu(H2O)'vertical bar Zr0.84Y0.16O1.92 vertical bar mu(O2)'',mu(H2O)'' where U is path-independent in any case and time-independent as long as the electrode equilibria prevail. Implications of the path- and time-dependence of U are discussed. (C) 2013 Elsevier B.V. All rights reserved.