We develop SOFC based on a NiO–YSZ anode support, a thin YSZ layer (5–10 micron) and a LaSrMnO3 cathode. Mn and Ni can dissolve into thin zirconia during high temperature fabrication. On cells, we consistently measured higher ohmic losses than expected from the YSZ resistivity. To investigate whether ionic conductivity of YSZ is affected, dense tape cast YSZ doped with 1 at.% Mn or 2 mol% NiO was fabricated and the conductivities in O2 and H2 measured between 300 and 850