The structural phase transition and ionic conductivity of 0.88ZrO(2)-(0.12 - x)Sc2O3-Al2O3 (0 less than or equal to x less than or equal to 0.005) was examined to clarify the mechanism of the cubic phase stabilization in this system. The temperature of the transition from rhombohedral to cubic decreases monotonously from 660 degrees C (x = 0) to 500 degrees C (x = 0.004) and no transition is observed at x = 0.005. The stabilization mechanism may be closely related to the strain induced in the crystalline lattice caused by adding the second dopant Al2O3. This is supported by the experimental result which reveals that the compositional dependence of the transition temperature in the 0.88ZrO(2)-(0.12 - x)Sc2O3-xM(2)O(3) system strongly depends on the ionic radius of second dopant.