Electrical conductivity of 10 at.% manganese doped yttria (8 mol%) stabilized zirconia (Mn-YSZ) has been investigated using electrochemical cell technique in 800-1000 degrees C and 1-10(-20) atm oxygen partial pressure (Po-2) range. The electrical conductivity increases according to PO21/G power law with increasing Po-2, in 1-10(-5) atm range, remains Po-2 independent in 10(-5)-10(-15) atm range, and slightly decreases with decreasing Po-2 in 10(-15)-10(-20) atm range. The deviation from Po-2(1/4) power law is attributed to the presence of multivalent state of manganese ions in 1-10(-5) atm Po-2 range. The electrical conductivity of Mn-YSZ is lower than that of yttria stabilized zirconia in reducing atmosphere. At lower oxygen partial pressures, lattice strain, defect association, and electron trapping results in decreased electrical conductivity. (C) 2013 Elsevier B.V. All rights reserved.