Yttria stabilized zirconia (YSZ) thin films of 20 to 90 nm thickness were prepared by pulsed laser deposition (PLD) on silicon substrates with a native silica layer. The high dc resistance of the silica interlayer causes strongly frequency dependent current lines between two stripe electrodes on the YSZ layer. This allows determination of the in-and across-plane conductivity of the YSZ film from a single impedance spectrum. The high frequency part of the impedance spectra corresponds to an across-plane measurement geometry while the low frequency part is governed by in-plane current flow. It is shown that the measured in-plane conductivity is about one order of magnitude lower than the across-plane bulk conductivity. This anisotropy is attributed to the blocking effect of grain boundaries in the columnar structured YSZ films. The activation energies of across-plane ionic conductivity (similar to 0.8 eV) are lower than those of in-plane conduction (similar to 1 eV). (C) 2012 The Electrochemical Society. [DOI: 10.11492.081204jes] All rights reserved.