The ionic conductivity in the system (1 - 0.08x -0.12y)ZrO2-0.08xY(2)O(3)-0.12yCaO (where x + y = 1 and y = 0-1) has been investigated using the complex impedance technique at 523-973 K. Doping CaO in the ZrO2-Y2O3 system may result in an increase in the activation energy for lattice conduction and depress the grain-boundary effect on conduction. Analysis of the temperature dependence of the lattice conductivity, according to the familiar Arrhenius equation, predicts that the examined ternary system map exhibit greater lattice conductivity than the ZrO2-Y2O3 binary system at higher temperatures. Preliminary explanations for these experimental phenomena and predictions also have been presented.