An insight into the electronic interaction between platinum nanoparticles and ionically conductive yttria-stabilized zirconia (YSZ) support is reported. To this end, Pt nanoparticles with four different crystallite sizes ranging from 1.9 to 6.7 nm were interfaced with YSZ resulting in <= 1 wt% Pt on YSZ. The obtained four Pt/YSZ systems were studied using X-ray photoelectron spectroscopy and the changes of the recorded spectra are discussed in details. Pt4f peak is detected in all cases at lower binding energies compared to the position of the peak of a platinum foil. More specifically, the Pt4f peak in the case of the smallest nanoparticles shifts 0.9 eV compared to the peak position of the Pt foil. Furthermore, small changes are detected on the Zr3d, Y3d and O1s spectra after Pt nanoparticle deposition. The XPS results are interpreted on the basis of charge transfer that occurs from the oxide support to the platinum nanoparticles, which may be responsible for the observed strong metal-support interaction (SMSI) between Pt and ionically conducting ceramics reported earlier for various catalytic reactions. (C) 2014 Elsevier B.V. All rights reserved.