Thin films of tin doped indium oxide (In2O3:Sn or ITO) were deposited by rf-magnetron sputtering from ceramic In2O3/SnO2 targets. Surface electronic properties were investigated using in situ photoelectron spectroscopy (XPS, UPS). Bulk properties, were analysed using electrical and optical measurements. While for a range of deposition parameters the ITO films clearly show degenerate bulk doping, the surfaces exhibit a Fermi level position well below the conduction band minimum. (C) 2004 Elsevier B.V. All rights reserved.