DC and ac impedance measurements were performed on yittria-stabilized ZrO2 electrolytes to separate bulk properties from interfacial phenomena. A Pt voltage probe was buried directly into the solid yittria-stabilizied ZrO2 electrolyte via screen-printing tape cast layers. DC measurements of solid oxide fuel cells were performed with an internal Pt voltage probe to determine ohmic and nonohmic drops for the total cell during operation. AC impedance measurements were also utilized to show a good correlation between the total cell impedance and the sum of the two half-cell impedances.