Pr-doped ZnO (ZnO:Pr) insulating thin films were prepared on glass and Si substrates by oxidation in air. The films were characterised by X-ray diffraction (XRD), energy dispersion X-ray fluorescence (EDXRF), and optical absorption spectroscopy. The molar ratio Pr/Zn of the samples was determined by the EDXRF method. The XRD study shows the formation of nanocrystalline (26-50nm) nc-Pr-doped ZnO. The optical and electrical conduction were explained by a slight change of stoichiometric composition. The nc-ZnO:Pr/Si heterojunctions are being Schottky barrier diodes (SBDs) and exhibited high rectification behaviour. The parameters describe the current pass through those SBDs were determined according to the available models. (C) 2009 Elsevier B.V. All rights reserved.