In the present study, the sintering of (ZrO2:8 mol%Y2O3)(1 -) (m)-(MgO)(m), YSZ-mMg composites, with m in the 0-30 mol% range, has been investigated by impedance spectroscopy (IS), dilatometry, and X-ray diffraction. Impedance diagrams were collected at 400 degrees C after heating the green compacts up to a selected sintering temperature, which was increased stepwise from 800 to 1400 degrees C. The combined experimental results revealed that the samples can be separated in two categories: below and above the solubility limit of MgO in the YSZ (m similar to 10). Moreover. important microstructural features associated with both the sintering process and solid solution formation of YSZ-mMgO samples were correlated to the electrical properties inferred by IS. (C) 2009 Elsevier B.V. All rights reserved.