It is demonstrated that resonance surface X-ray scattering (RSXS) in which incident X-ray energy close to the Pt L-III absorption edge (11 55 keV) is used is very useful for the determination of the structure of electrodeposited Pt thin layers on a Au(1 1 1) surface This technique was applied to characterize the structure of electrodeposited Pt layers on Au(1 1 1) substrates prepared under two extreme conditions which are known to provide rough and atomically fiat layers Detailed structural information was obtained by RSXS measurements and it was confirmed that the structures of the Pt layers were as reported Pt atoms of the atomically flat monolayer were found to be situated at the threefold hollow cubic closest packing (ccp) sites of the Au(1 1 1)-(1 x 1) surface (C) 2010 Elsevier Ltd All rights reserved