The electrical conductivity of 10% Sr and 10% Mg doped LaAlO3 (LSAM9191) was measured using impedance spectroscopy at temperatures between 400 and 1000 degreesC. Between 800 and 1000 degreesC, the conductivity was also measured as a function of oxygen partial pressure (P-O2). Below 550 degreesC, the grain boundary resistance mostly determined the overall conductivity that nearly disappeared above 800 degreesC. In the temperature region where the sample resistance is mostly determined by grain property, LSAM9191 was an oxygen ion conductor at low P-O2 and a mixed conductor at high P-O2. With increasing temperature, the ionic conductioh region only slightly increased. Thus, LSAM9191 is a promising material as an oxygen ion conductor at high temperature in low P-O2.