The structural, thermal, and electrical characteristics of calcium-and cobalt-doped yttrium chromites were studied for potential use as interconnect material in high temperature solid oxide fuel cells as well as other high temperature electrochemical and thermoelectric devices. The Y0.8Ca0.2Cr1-xCoxO3 +/-delta (x = 0, 0.1, 0.2, 0.3) compositions formed single-phase orthorhombic perovskite structures in a wide range of oxygen pressures. Sintering behavior was remarkably enhanced as a result of cobalt substitution for chromium, and densities 95 and 97% of theoretical density were obtained after sintering at 1300 degrees C in air, when x was 0.2 and 0.3, respectively. The electrical conductivity in both oxidizing and reducing atmospheres was significantly improved with cobalt additions, and was 49 and 10 S/cm at 850 degrees C and 55 and 14 S/cm at 950 degrees C in air and forming gas, respectively, for x = 0.2. The conductivity increase upon cobalt substitution for chromium was attributed to the charge carrier density increase as confirmed by Seebeck measurements. The thermal expansion coefficient was increased with cobalt content and closely matched to that of an 8 mol % yttria-stabilized zirconia (YSZ) electrolyte for 0.1 <= x <= 0.2. For x <= 0.2, Y0.8Ca0.2Cr1-xCoxO3 +/-delta and YSZ were found to be chemically compatible for firing temperatures to at least 1400 degrees C. (C) 2010 The Electrochemical Society. [DOI: 10.1149/1.3337156] All rights reserved.