Electrical conductivity of 10 at.% manganese doped yttria (8 mol%) stabilized zirconia (Mn-YSZ) has been investigated using electrochemical cell technique in 800-1000 C and 1-10-20 atm oxygen partial pressure PO2 range. The electrical conductivity increases according to PO216 power law with increasing PO2 in 1-10 -5 atm range, remains PO2 independent in 10 -5-10-15 atm range, and slightly decreases with decreasing PO2 in 10-15-10-20 atm range. The deviation from PO214 power law is attributed to the presence of multivalent state of manganese ions in 1-10- 5 atm PO2 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. © 2013 Elsevier B.V.