Mixtures of alpha-Al2O3 and La0.8Sr0.2Ga0.8Mg0.2O3-delta, with alpha-Al2O3 concentrations ranging from 1 to 20 wt.%, were uniaxially and isostatically pressed and finally sintered at 1500 degreesC for 4 h. The phase composition and microstructure were investigated by X-ray powder diffraction and scanning electron microscopy techniques. The electrical properties were studied by complex impedance spectroscopy in a wide range of temperatures (200-800 degreesC) in air. In the sintered bodies pure alpha-Al2O3 was not detected; the partial substitution of Al for Ga was suggested entailing the formation of the solid solutions of perovskite-type (La0.8Sr0.2)(Ga1-x-yAlxMgy)O3-delta and La0.8Sr0.2Ga1-xAlx O3-delta. alpha-Al2O3 added to La0.8Sr0.2Ga0.8Mg0.2O3-delta inhibited the grain growth of the majority phase. Under isothermal conditions, the electrical conductivity decreases with increasing alumina content, while the activation energies increase. (C) 2004 Elsevier B.V. All rights reserved.