Surface sputtering is a commonly used technique for surface analysis. The standard method of Ar+ sputtering was found to produce surface changes or damages. In this work, nickel-phosphorus films are characterized by X-ray photoelectron spectroscopy (XPS) angle resolved technique before and after sputtering. A method is presented to determine the correct atomic ratio between Ni and P in the surface layers, taking into account that nickel atoms are mainly displaced toward inner layers, as a consequence of 4-5 at.% argon ion implantation within top 1.5-3.7 nm from the surface. The experimental argon implantation and nickel displacement ranges match with Lindhard-Scharff model. Metallic nickel formation in the first layer is detected after sputtering by X-ray diffractometry at low glancing angle. No detectable difference was found between the binding energy of nickel in the metallic state and in the Ni-P coating, showing a similar chemical state for nickel in both conditions. (C) 2003 Elsevier Science B.V All rights reserved.